You can also delete the Plan using the DELETE_PLAN procedure available in the DBMS_RESOURCE_MANAGER package.

DECLARE

PLAN VARCHAR2(200) ;

BEGIN

PLAN := 'NEW_PLAN' ;

SYS.DBMS_RESOURCE_MANAGER.CLEAR_PENDING_AREA ;

SYS.DBMS_RESOURCE_MANAGER.CREATE_PENDING_AREA ;

 SYS.DBMS_RESOURCE_MANAGER.DELETE_PLAN ( PLAN ) ;

 SYS.DBMS_RESOURCE_MANAGER.SUBMIT_PENDING_AREA ;

COMMIT ;

END ;