Killing session cookies, caches and everything.

Hi !! I'm working with php 4.0.4pl1 under windows NT, and I really need big help here. I can't delete, kill, erase the session after the user end shopping. I try session_unset, session_destroy and header ("Expires: Fri,09 Sep 1966 06:09:06 GMT"); header ("Last-Modified: " . gmdate("D, d M Y H:i:s") . GMT"); header ("Cache-Control: no-cache, must revalidate"); header ("Pragma: no-cache"); and all kind of stuff even I wrote a script that delete the session file under /tmp but the session is still alive in the browser so the cookies are the problem. Can anybody plase tell me a way to delete ALL the cookies cached in disk/ram in order my app work ? I'm in a hurry and I'll appreciate any help. Thanks in advance. Angel.