Use DeleteDBParameterGroup with an AWS SDK or CLI

    /// <summary>
    /// Delete a DB parameter group. The group cannot be a default DB parameter group
    /// or be associated with any DB instances.
    /// </summary>
    /// <param name="name">Name of the DB parameter group.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> DeleteDBParameterGroup(string name)
    {
        var response = await _amazonRDS.DeleteDBParameterGroupAsync(
            new DeleteDBParameterGroupRequest()
            {
                DBParameterGroupName = name,
            });
        return response.HttpStatusCode == 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::DeleteDBParameterGroupRequest request;
        request.SetDBParameterGroupName(parameterGroupName);

        Aws::RDS::Model::DeleteDBParameterGroupOutcome outcome =
                client.DeleteDBParameterGroup(request);

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

To delete a DB parameter group

The following command example deletes a DB parameter group.

aws rds delete-db-parameter-group \
    --db-parameter-group-name mydbparametergroup

This command produces no output.

For more information, see Working with DB Parameter Groups in the Amazon RDS User Guide.

import (
	"context"
	"errors"
	"log"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/service/rds"
	"github.com/aws/aws-sdk-go-v2/service/rds/types"
)

type DbInstances struct {
	RdsClient *rds.Client
}



// DeleteParameterGroup deletes the named DB parameter group.
func (instances *DbInstances) DeleteParameterGroup(ctx context.Context, parameterGroupName string) error {
	_, err := instances.RdsClient.DeleteDBParameterGroup(ctx,
		&rds.DeleteDBParameterGroupInput{
			DBParameterGroupName: aws.String(parameterGroupName),
		})
	if err != nil {
		log.Printf("Couldn't delete parameter group %v: %v\n", parameterGroupName, err)
		return err
	} else {
		return nil
	}
}

    // Delete the parameter group after database has been deleted.
    // An exception is thrown if you attempt to delete the para group while database
    // exists.
    public static void deleteParaGroup(RdsClient rdsClient, String dbGroupName, String dbARN)
            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(dbARN) == 0) {
                        System.out.println(dbARN + " 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++;
                }
            }

            // Delete the para group.
            DeleteDbParameterGroupRequest parameterGroupRequest = DeleteDbParameterGroupRequest.builder()
                    .dbParameterGroupName(dbGroupName)
                    .build();

            rdsClient.deleteDBParameterGroup(parameterGroupRequest);
            System.out.println(dbGroupName + " was deleted.");

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

class InstanceWrapper:
    """Encapsulates Amazon RDS DB instance actions."""

    def __init__(self, rds_client):
        """
        :param rds_client: A Boto3 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 parameter group.

        :param parameter_group_name: The name of the parameter group to delete.
        :return: Data about the parameter group.
        """
        try:
            self.rds_client.delete_db_parameter_group(
                DBParameterGroupName=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