destroying session variables

[phppixel]

if i open two browser windows and login in both windows, then logout of one and refresh the second one, i am still logged in in the second one
i guess the session varibles are stored with different names
is there anyway this can be overcome using session variables?

logout code:
<?php
session_start();
unset($HTTP_SESSION_VARS['valid_user']);
unset($HTTP_POST_VARS['username']);
unset($HTTP_SESSION_VARS['access_level'] );

session_destroy();
?>

[LordShryku]

Instead of unsetting each one, try just using

session_start();
$_SESSION = array();
session_detroy();