With a single click this simple script will do a multi-logout of:
Moodle
Elgg
2 MyBB's and
(not) Drupal.
    <?php
setcookie( 'Elgg', '', -3600, '/', '.domain.com', false, false);
setcookie( 'http_auth_ext_complete', '1', -3600, '/d/', '.domain.com', false, false);
// setcookie( 'http_auth_ext_complete', '1', -3600, '/d/', 'domain.com', false, false); 
setcookie( 'mybbuser', '', -3600, '/', '.domain.com', false, false);
setcookie( 'mybbuser', '', -3600, '/bb/', '.domain.com', false, false);
   // unset all 3 Moodle cookies, the lazy way
    if (isset($_SERVER['HTTP_COOKIE'])) {
        $cookies = explode(';', $_SERVER['HTTP_COOKIE']);
        foreach($cookies as $cookie) {
            $parts = explode('=', $cookie);
            $name = trim($parts[0]);
            setcookie($name, '', time()-1000);
            setcookie($name, '', time()-1000, '/');
        }
    }
    ?>
This works on four sites but the Drupal cookie won't quit. How can I do the same with Drupal?
Note: Drupal uses 'host' instead of 'domain', neither with or without the '.' works so far.
Thank you.