Piwik\Notification\Manager::removeNotification PHP Method

    private static function removeNotification($id)
    {
        if (array_key_exists($id, self::$notifications)) {
            unset(self::$notifications[$id]);
        }
        if (self::isSessionEnabled()) {
            $session = static::getSession();
            if (array_key_exists($id, $session->notifications)) {
                unset($session->notifications[$id]);
            }
        }
    }