Remove Job from another user : DBMS_IJOB.REMOVE

SQL> exec dbms_job.remove(40682);
BEGIN dbms_job.remove(40682); END;

*
ERROR at line 1:
ORA-23421: job number 40682 is not a job in the job queue
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 86
ORA-06512: at "SYS.DBMS_IJOB", line 687
ORA-06512: at "SYS.DBMS_JOB", line 174
ORA-06512: at line 1


SQL> EXECUTE SYS.DBMS_IJOB.REMOVE (40682);

PL/SQL procedure successfully completed.

SQL>