public function deleteAll($idSite)
    {
        Piwik::checkUserHasSuperUserAccess();

        $this->checkSingleIdSite($idSite, $extraMessage = "Note: Cannot delete annotations from multiple sites.");

        $annotations = new AnnotationList($idSite);

        // remove the notes & save the list
        $annotations->removeAll($idSite);
        $annotations->save($idSite);
    }