Use DetachThingPrincipal with an Amazon SDK or CLI

    /// <summary>
    /// Detaches a certificate from an IoT Thing.
    /// </summary>
    /// <param name="thingName">The name of the Thing.</param>
    /// <param name="certificateArn">The ARN of the certificate to detach.</param>
    /// <returns>True if successful, false otherwise.</returns>
    public async Task<bool> DetachThingPrincipalAsync(string thingName, string certificateArn)
    {
        try
        {
            var request = new DetachThingPrincipalRequest
            {
                ThingName = thingName,
                Principal = certificateArn
            };

            await _amazonIoT.DetachThingPrincipalAsync(request);
            _logger.LogInformation($"Detached certificate {certificateArn} from Thing {thingName}");
            return true;
        }
        catch (Amazon.IoT.Model.ResourceNotFoundException ex)
        {
            _logger.LogError($"Cannot detach certificate - resource not found: {ex.Message}");
            return false;
        }
        catch (Exception ex)
        {
            _logger.LogError($"Couldn't detach certificate from Thing. Here's why: {ex.Message}");
            return false;
        }
    }

//! Detach a principal from an AWS IoT thing.
/*!
  \param principal: A principal to detach.
  \param thingName: The name for the thing.
  \param clientConfiguration: AWS client configuration.
  \return bool: Function succeeded.
 */
bool AwsDoc::IoT::detachThingPrincipal(const Aws::String &principal,
                                       const Aws::String &thingName,
                                       const Aws::Client::ClientConfiguration &clientConfiguration) {
    Aws::IoT::IoTClient iotClient(clientConfiguration);

    Aws::IoT::Model::DetachThingPrincipalRequest detachThingPrincipalRequest;
    detachThingPrincipalRequest.SetThingName(thingName);
    detachThingPrincipalRequest.SetPrincipal(principal);

    Aws::IoT::Model::DetachThingPrincipalOutcome outcome = iotClient.DetachThingPrincipal(
            detachThingPrincipalRequest);

    if (outcome.IsSuccess()) {
        std::cout << "Successfully detached principal " << principal << " from thing "
                  << thingName << std::endl;
    }
    else {
        std::cerr << "Failed to detach principal " << principal << " from thing "
                  << thingName << ": "
                  << outcome.GetError().GetMessage() << std::endl;
    }

    return outcome.IsSuccess();
}

To detach a certificate/principal from a thing

The following detach-thing-principal example removes a certificate that represents a principal from the specified thing.

aws iot detach-thing-principal \
    --thing-name "MyLightBulb" \
    --principal "arn:aws:iot:us-west-2:123456789012:cert/604c48437a57b7d5fc5d137c5be75011c6ee67c9a6943683a1acb4b1626bac36"

This command produces no output.

For more information, see How to Manage Things with the Registry in the Amazon IoT Developers Guide.

    /**
     * Detaches a principal (certificate) from an IoT Thing asynchronously.
     *
     * @param thingName The name of the IoT Thing.
     * @param certificateArn The ARN of the certificate to detach.
     *
     * This method initiates an asynchronous request to detach a certificate from an IoT Thing.
     * If the detachment is successful, it prints a confirmation message.
     * If an exception occurs, it prints the error message.
     */
    public void detachThingPrincipal(String thingName, String certificateArn) {
        DetachThingPrincipalRequest thingPrincipalRequest = DetachThingPrincipalRequest.builder()
            .principal(certificateArn)
            .thingName(thingName)
            .build();

        CompletableFuture<DetachThingPrincipalResponse> future = getAsyncClient().detachThingPrincipal(thingPrincipalRequest);
        future.whenComplete((voidResult, ex) -> {
            if (ex == null) {
                System.out.println(certificateArn + " was successfully removed from " + thingName);
            } else {
                Throwable cause = ex.getCause();
                if (cause instanceof IotException) {
                    System.err.println(((IotException) cause).awsErrorDetails().errorMessage());
                } else {
                    System.err.println("Unexpected error: " + ex.getMessage());
                }
            }
        });

        future.join();
    }

suspend fun detachThingPrincipal(
    thingNameVal: String,
    certificateArn: String,
) {
    val thingPrincipalRequest =
        DetachThingPrincipalRequest {
            principal = certificateArn
            thingName = thingNameVal
        }

    IotClient.fromEnvironment { region = "us-east-1" }.use { iotClient ->
        iotClient.detachThingPrincipal(thingPrincipalRequest)
        println("$certificateArn was successfully removed from $thingNameVal")
    }
}

class IoTWrapper:
    """Encapsulates AWS IoT actions."""

    def __init__(self, iot_client, iot_data_client=None):
        """
        :param iot_client: A Boto3 AWS IoT client.
        :param iot_data_client: A Boto3 AWS IoT Data Plane client.
        """
        self.iot_client = iot_client
        self.iot_data_client = iot_data_client

    @classmethod
    def from_client(cls):
        iot_client = boto3.client("iot")
        iot_data_client = boto3.client("iot-data")
        return cls(iot_client, iot_data_client)

    def detach_thing_principal(self, thing_name, principal):
        """
        Detaches a certificate from an AWS IoT thing.

        :param thing_name: The name of the thing.
        :param principal: The ARN of the certificate.
        """
        try:
            self.iot_client.detach_thing_principal(
                thingName=thing_name, principal=principal
            )
            logger.info("Detached principal %s from thing %s.", principal, thing_name)
        except ClientError as err:
            if err.response["Error"]["Code"] == "ResourceNotFoundException":
                logger.error("Cannot detach principal. Resource not found.")
                return
            logger.error(
                "Couldn't detach principal from thing. Here's why: %s: %s",
                err.response["Error"]["Code"],
                err.response["Error"]["Message"],
            )
            raise