/**
  * Sends an API request for removing the notification from the api server, 
  * thereby causing any future calls to getNotificationInfo() to fail. Also,
  * prevents the api from sending any further notifications. 
  *
  * Unless this method is called, the api will keep sending the same 
  * notification id indefinitely.
  * 
  * @param string $notificationId notification id
  *
  * @return array api response
  * @throws ServiceException if api request was not successful
  */
 public function deleteNotification($notificationId)
 {
     $urlPath = '/rest/3/Commerce/Payment/Notifications/' . $notificationId;
     $url = $this->getFqdn() . $urlPath;
     $req = new RESTFulRequest($url);
     $req->setHttpMethod(RESTFulRequest::HTTP_METHOD_PUT);
     $req->setHeader('Accept', 'application/json');
     $req->addAuthorizationHeader($this->token);
     $result = $req->sendRequest();
     return $this->parseResult($result);
 }