This is done using the procedure DELETE_CONSUMER_GROUP.

DECLARE

CONSUMER_GROUP VARCHAR2(200);

NEW_COMMENT VARCHAR2(200);

BEGIN

CONSUMER_GROUP := 'NEW_GROUP';

SYS.DBMS_RESOURCE_MANAGER.CLEAR_PENDING_AREA;

SYS.DBMS_RESOURCE_MANAGER.CREATE_PENDING_AREA;

SYS.DBMS_RESOURCE_MANAGER.DELETE_CONSUMER_GROUP ( CONSUMER_GROUP );

SYS.DBMS_RESOURCE_MANAGER.SUBMIT_PENDING_AREA;

COMMIT;

END;