Use DeleteDBClusterParameterGroup with an Amazon SDK or command line tool

    /// <summary>
    /// Delete a particular parameter group by name.
    /// </summary>
    /// <param name="groupName">The name of the parameter group.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> DeleteClusterParameterGroupByNameAsync(string groupName)
    {
        var request = new DeleteDBClusterParameterGroupRequest
        {
            DBClusterParameterGroupName = groupName,
        };

        var response = await _amazonRDS.DeleteDBClusterParameterGroupAsync(request);
        return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
    }

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::RDS::RDSClient client(clientConfig);

        Aws::RDS::Model::DeleteDBClusterParameterGroupRequest request;
        request.SetDBClusterParameterGroupName(parameterGroupName);

        Aws::RDS::Model::DeleteDBClusterParameterGroupOutcome outcome =
                client.DeleteDBClusterParameterGroup(request);

        if (outcome.IsSuccess()) {
            std::cout << "The DB parameter group was successfully deleted."
                      << std::endl;
        }
        else {
            std::cerr << "Error with Aurora::DeleteDBClusterParameterGroup. "
                      << outcome.GetError().GetMessage()
                      << std::endl;
            result = false;
        }

type DbClusters struct {
	AuroraClient *rds.Client
}



// DeleteParameterGroup deletes the named DB cluster parameter group.
func (clusters *DbClusters) DeleteParameterGroup(parameterGroupName string) error {
	_, err := clusters.AuroraClient.DeleteDBClusterParameterGroup(context.TODO(),
		&rds.DeleteDBClusterParameterGroupInput{
			DBClusterParameterGroupName: aws.String(parameterGroupName),
		})
	if err != nil {
		log.Printf("Couldn't delete parameter group %v: %v\n", parameterGroupName, err)
		return err
	} else {
		return nil
	}
}

    public static void deleteDBClusterGroup(RdsClient rdsClient, String dbClusterGroupName, String clusterDBARN)
            throws InterruptedException {
        try {
            boolean isDataDel = false;
            boolean didFind;
            String instanceARN;

            // Make sure that the database has been deleted.
            while (!isDataDel) {
                DescribeDbInstancesResponse response = rdsClient.describeDBInstances();
                List<DBInstance> instanceList = response.dbInstances();
                int listSize = instanceList.size();
                didFind = false;
                int index = 1;
                for (DBInstance instance : instanceList) {
                    instanceARN = instance.dbInstanceArn();
                    if (instanceARN.compareTo(clusterDBARN) == 0) {
                        System.out.println(clusterDBARN + " still exists");
                        didFind = true;
                    }
                    if ((index == listSize) && (!didFind)) {
                        // Went through the entire list and did not find the database ARN.
                        isDataDel = true;
                    }
                    Thread.sleep(sleepTime * 1000);
                    index++;
                }
            }

            DeleteDbClusterParameterGroupRequest clusterParameterGroupRequest = DeleteDbClusterParameterGroupRequest
                    .builder()
                    .dbClusterParameterGroupName(dbClusterGroupName)
                    .build();

            rdsClient.deleteDBClusterParameterGroup(clusterParameterGroupRequest);
            System.out.println(dbClusterGroupName + " was deleted.");

        } catch (RdsException e) {
            System.out.println(e.getLocalizedMessage());
            System.exit(1);
        }
    }

@Throws(InterruptedException::class)
suspend fun deleteDBClusterGroup(dbClusterGroupName: String, clusterDBARN: String) {
    var isDataDel = false
    var didFind: Boolean
    var instanceARN: String

    RdsClient { region = "us-west-2" }.use { rdsClient ->
        // Make sure that the database has been deleted.
        while (!isDataDel) {
            val response = rdsClient.describeDbInstances()
            val instanceList = response.dbInstances
            val listSize = instanceList?.size
            isDataDel = false
            didFind = false
            var index = 1
            if (instanceList != null) {
                for (instance in instanceList) {
                    instanceARN = instance.dbInstanceArn.toString()
                    if (instanceARN.compareTo(clusterDBARN) == 0) {
                        println("$clusterDBARN still exists")
                        didFind = true
                    }
                    if (index == listSize && !didFind) {
                        // Went through the entire list and did not find the database ARN.
                        isDataDel = true
                    }
                    delay(slTime * 1000)
                    index++
                }
            }
        }
        val clusterParameterGroupRequest = DeleteDbClusterParameterGroupRequest {
            dbClusterParameterGroupName = dbClusterGroupName
        }

        rdsClient.deleteDbClusterParameterGroup(clusterParameterGroupRequest)
        println("$dbClusterGroupName was deleted.")
    }
}

class AuroraWrapper:
    """Encapsulates Aurora DB cluster actions."""

    def __init__(self, rds_client):
        """
        :param rds_client: A Boto3 Amazon Relational Database Service (Amazon RDS) client.
        """
        self.rds_client = rds_client

    @classmethod
    def from_client(cls):
        """
        Instantiates this class from a Boto3 client.
        """
        rds_client = boto3.client("rds")
        return cls(rds_client)


    def delete_parameter_group(self, parameter_group_name):
        """
        Deletes a DB cluster parameter group.

        :param parameter_group_name: The name of the parameter group to delete.
        :return: Data about the parameter group.
        """
        try:
            response = self.rds_client.delete_db_cluster_parameter_group(
                DBClusterParameterGroupName=parameter_group_name
            )
        except ClientError as err:
            logger.error(
                "Couldn't delete parameter group %s. Here's why: %s: %s",
                parameter_group_name,
                err.response["Error"]["Code"],
                err.response["Error"]["Message"],
            )
            raise
        else:
            return response

    pub async fn clean_up(self) -> Result<(), Vec<ScenarioError>> {
        let mut clean_up_errors: Vec<ScenarioError> = vec![];

        // Delete the instance. rds.DeleteDbInstance.
        let delete_db_instance = self
            .rds
            .delete_db_instance(
                self.db_instance_identifier
                    .as_deref()
                    .expect("instance identifier"),
            )
            .await;
        if let Err(err) = delete_db_instance {
            let identifier = self
                .db_instance_identifier
                .as_deref()
                .unwrap_or("Missing Instance Identifier");
            let message = format!("failed to delete db instance {identifier}");
            clean_up_errors.push(ScenarioError::new(message, &err));
        } else {
            // Wait for the instance to delete
            let waiter = Waiter::default();
            while waiter.sleep().await.is_ok() {
                let describe_db_instances = self.rds.describe_db_instances().await;
                if let Err(err) = describe_db_instances {
                    clean_up_errors.push(ScenarioError::new(
                        "Failed to check instance state during deletion",
                        &err,
                    ));
                    break;
                }
                let db_instances = describe_db_instances
                    .unwrap()
                    .db_instances()
                    .iter()
                    .filter(|instance| instance.db_cluster_identifier == self.db_cluster_identifier)
                    .cloned()
                    .collect::<Vec<DbInstance>>();

                if db_instances.is_empty() {
                    trace!("Delete Instance waited and no instances were found");
                    break;
                }
                match db_instances.first().unwrap().db_instance_status() {
                    Some("Deleting") => continue,
                    Some(status) => {
                        info!("Attempting to delete but instances is in {status}");
                        continue;
                    }
                    None => {
                        warn!("No status for DB instance");
                        break;
                    }
                }
            }
        }

        // Delete the DB cluster. rds.DeleteDbCluster.
        let delete_db_cluster = self
            .rds
            .delete_db_cluster(
                self.db_cluster_identifier
                    .as_deref()
                    .expect("cluster identifier"),
            )
            .await;

        if let Err(err) = delete_db_cluster {
            let identifier = self
                .db_cluster_identifier
                .as_deref()
                .unwrap_or("Missing DB Cluster Identifier");
            let message = format!("failed to delete db cluster {identifier}");
            clean_up_errors.push(ScenarioError::new(message, &err));
        } else {
            // Wait for the instance and cluster to fully delete. rds.DescribeDbInstances and rds.DescribeDbClusters until both are not found.
            let waiter = Waiter::default();
            while waiter.sleep().await.is_ok() {
                let describe_db_clusters = self
                    .rds
                    .describe_db_clusters(
                        self.db_cluster_identifier
                            .as_deref()
                            .expect("cluster identifier"),
                    )
                    .await;
                if let Err(err) = describe_db_clusters {
                    clean_up_errors.push(ScenarioError::new(
                        "Failed to check cluster state during deletion",
                        &err,
                    ));
                    break;
                }
                let describe_db_clusters = describe_db_clusters.unwrap();
                let db_clusters = describe_db_clusters.db_clusters();
                if db_clusters.is_empty() {
                    trace!("Delete cluster waited and no clusters were found");
                    break;
                }
                match db_clusters.first().unwrap().status() {
                    Some("Deleting") => continue,
                    Some(status) => {
                        info!("Attempting to delete but clusters is in {status}");
                        continue;
                    }
                    None => {
                        warn!("No status for DB cluster");
                        break;
                    }
                }
            }
        }

        // Delete the DB cluster parameter group. rds.DeleteDbClusterParameterGroup.
        let delete_db_cluster_parameter_group = self
            .rds
            .delete_db_cluster_parameter_group(
                self.db_cluster_parameter_group
                    .map(|g| {
                        g.db_cluster_parameter_group_name
                            .unwrap_or_else(|| DB_CLUSTER_PARAMETER_GROUP_NAME.to_string())
                    })
                    .as_deref()
                    .expect("cluster parameter group name"),
            )
            .await;
        if let Err(error) = delete_db_cluster_parameter_group {
            clean_up_errors.push(ScenarioError::new(
                "Failed to delete the db cluster parameter group",
                &error,
            ))
        }

        if clean_up_errors.is_empty() {
            Ok(())
        } else {
            Err(clean_up_errors)
        }
    }

    pub async fn delete_db_cluster_parameter_group(
        &self,
        name: &str,
    ) -> Result<DeleteDbClusterParameterGroupOutput, SdkError<DeleteDBClusterParameterGroupError>>
    {
        self.inner
            .delete_db_cluster_parameter_group()
            .db_cluster_parameter_group_name(name)
            .send()
            .await
    }

#[tokio::test]
async fn test_scenario_clean_up() {
    let mut mock_rds = MockRdsImpl::default();

    mock_rds
        .expect_delete_db_instance()
        .with(eq("MockInstance"))
        .return_once(|_| Ok(DeleteDbInstanceOutput::builder().build()));

    mock_rds
        .expect_describe_db_instances()
        .with()
        .times(1)
        .returning(|| {
            Ok(DescribeDbInstancesOutput::builder()
                .db_instances(
                    DbInstance::builder()
                        .db_cluster_identifier("MockCluster")
                        .db_instance_status("Deleting")
                        .build(),
                )
                .build())
        })
        .with()
        .times(1)
        .returning(|| Ok(DescribeDbInstancesOutput::builder().build()));

    mock_rds
        .expect_delete_db_cluster()
        .with(eq("MockCluster"))
        .return_once(|_| Ok(DeleteDbClusterOutput::builder().build()));

    mock_rds
        .expect_describe_db_clusters()
        .with(eq("MockCluster"))
        .times(1)
        .returning(|id| {
            Ok(DescribeDbClustersOutput::builder()
                .db_clusters(
                    DbCluster::builder()
                        .db_cluster_identifier(id)
                        .status("Deleting")
                        .build(),
                )
                .build())
        })
        .with(eq("MockCluster"))
        .times(1)
        .returning(|_| Ok(DescribeDbClustersOutput::builder().build()));

    mock_rds
        .expect_delete_db_cluster_parameter_group()
        .with(eq("MockParamGroup"))
        .return_once(|_| Ok(DeleteDbClusterParameterGroupOutput::builder().build()));

    let mut scenario = AuroraScenario::new(mock_rds);
    scenario.db_cluster_identifier = Some(String::from("MockCluster"));
    scenario.db_instance_identifier = Some(String::from("MockInstance"));
    scenario.db_cluster_parameter_group = Some(
        DbClusterParameterGroup::builder()
            .db_cluster_parameter_group_name("MockParamGroup")
            .build(),
    );

    tokio::time::pause();
    let assertions = tokio::spawn(async move {
        let clean_up = scenario.clean_up().await;
        assert!(clean_up.is_ok());
    });

    tokio::time::advance(Duration::from_secs(1)).await; // Wait for first Describe Instances
    tokio::time::advance(Duration::from_secs(1)).await; // Wait for second Describe Instances
    tokio::time::advance(Duration::from_secs(1)).await; // Wait for first Describe Cluster
    tokio::time::advance(Duration::from_secs(1)).await; // Wait for second Describe Cluster
    tokio::time::resume();
    let _ = assertions.await;
}

#[tokio::test]
async fn test_scenario_clean_up_errors() {
    let mut mock_rds = MockRdsImpl::default();

    mock_rds
        .expect_delete_db_instance()
        .with(eq("MockInstance"))
        .return_once(|_| Ok(DeleteDbInstanceOutput::builder().build()));

    mock_rds
        .expect_describe_db_instances()
        .with()
        .times(1)
        .returning(|| {
            Ok(DescribeDbInstancesOutput::builder()
                .db_instances(
                    DbInstance::builder()
                        .db_cluster_identifier("MockCluster")
                        .db_instance_status("Deleting")
                        .build(),
                )
                .build())
        })
        .with()
        .times(1)
        .returning(|| {
            Err(SdkError::service_error(
                DescribeDBInstancesError::unhandled(Box::new(Error::new(
                    ErrorKind::Other,
                    "describe db instances error",
                ))),
                Response::new(StatusCode::try_from(400).unwrap(), SdkBody::empty()),
            ))
        });

    mock_rds
        .expect_delete_db_cluster()
        .with(eq("MockCluster"))
        .return_once(|_| Ok(DeleteDbClusterOutput::builder().build()));

    mock_rds
        .expect_describe_db_clusters()
        .with(eq("MockCluster"))
        .times(1)
        .returning(|id| {
            Ok(DescribeDbClustersOutput::builder()
                .db_clusters(
                    DbCluster::builder()
                        .db_cluster_identifier(id)
                        .status("Deleting")
                        .build(),
                )
                .build())
        })
        .with(eq("MockCluster"))
        .times(1)
        .returning(|_| {
            Err(SdkError::service_error(
                DescribeDBClustersError::unhandled(Box::new(Error::new(
                    ErrorKind::Other,
                    "describe db clusters error",
                ))),
                Response::new(StatusCode::try_from(400).unwrap(), SdkBody::empty()),
            ))
        });

    mock_rds
        .expect_delete_db_cluster_parameter_group()
        .with(eq("MockParamGroup"))
        .return_once(|_| Ok(DeleteDbClusterParameterGroupOutput::builder().build()));

    let mut scenario = AuroraScenario::new(mock_rds);
    scenario.db_cluster_identifier = Some(String::from("MockCluster"));
    scenario.db_instance_identifier = Some(String::from("MockInstance"));
    scenario.db_cluster_parameter_group = Some(
        DbClusterParameterGroup::builder()
            .db_cluster_parameter_group_name("MockParamGroup")
            .build(),
    );

    tokio::time::pause();
    let assertions = tokio::spawn(async move {
        let clean_up = scenario.clean_up().await;
        assert!(clean_up.is_err());
        let errs = clean_up.unwrap_err();
        assert_eq!(errs.len(), 2);
        assert_matches!(errs.get(0), Some(ScenarioError {message, context: _}) if message == "Failed to check instance state during deletion");
        assert_matches!(errs.get(1), Some(ScenarioError {message, context: _}) if message == "Failed to check cluster state during deletion");
    });

    tokio::time::advance(Duration::from_secs(1)).await; // Wait for first Describe Instances
    tokio::time::advance(Duration::from_secs(1)).await; // Wait for second Describe Instances
    tokio::time::advance(Duration::from_secs(1)).await; // Wait for first Describe Cluster
    tokio::time::advance(Duration::from_secs(1)).await; // Wait for second Describe Cluster
    tokio::time::resume();
    let _ = assertions.await;
}