how to disable employee from backend

Hi,

Can you please let me know how to disable employee from backend temporarily?

We would like to use certain flags on S_CONTACT OR S_USER, but could not make it work.

We tried with the each of the below one (and three flags in conjunction too), but no luck.

Can you please advice?

UPDATE SIEBEl.S_CONTACT SET EMP_FLG='N' WHERE  PAR_ROW_ID = '<>';

COMMIT;

UPDATE SIEBEL.S_USER SET USER_FLG='N' WHERE PAR_ROW_ID='<>';

COMMIT;

UPDATE SIEBEL.S_CONTACT SET ACTIVE_FLG='Y' WHERE PAR_ROW_ID='<>';

COMMIT;