session_unset Free all session variables &reftitle.description; boolsession_unset The session_unset function frees all session variables currently registered. &reftitle.parameters; &no.function.parameters; &reftitle.returnvalues; &return.success; &reftitle.changelog; &Version; &Description; 7.2.0 The return type of this function is bool now. Formerly, it has been void. &reftitle.notes; If $_SESSION is used, use unset to unregister a session variable, i.e. unset ($_SESSION['varname']);. Do NOT unset the whole $_SESSION with unset($_SESSION) as this will disable the registering of session variables through the $_SESSION superglobal. Only use session_unset for older deprecated code that does not use $_SESSION.