session_destroy Destroys all data registered to a session boolsession_destroy session_destroy destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie. In order to kill the session altogether, like to log the user out, the session id must also be unset. If a cookie is used to propagate the session id (default behavior), then the session cookie must be deleted. setcookie may be used for that. &return.success; ]]> Only use session_unset for older deprecated code that does not use $_SESSION. See also unset and setcookie.