/**
  * Removes a test taker from a delivery
  *
  * @throws \common_Exception
  * @throws \oat\oatbox\service\ServiceNotFoundException
  */
 public function removeTestTakers()
 {
     $deliveryId = $this->getRequestParameter('delivery');
     $testTakers = $this->getRequestParameter('testtaker');
     $testCenterId = $this->getRequestParameter('testCenter');
     if (!is_array($testTakers)) {
         $testTakers = array($testTakers);
     }
     try {
         $removed = DeliveryHelper::unassignTestTakers($testTakers, $deliveryId, $testCenterId);
         $notRemoved = array_diff($testTakers, $removed);
         $this->returnJson(array('success' => !count($notRemoved), 'processed' => $removed, 'unprocessed' => $notRemoved));
     } catch (ServiceNotFoundException $e) {
         \common_Logger::w('No delivery service defined for proctoring');
         $this->returnError('Proctoring interface not available');
     }
 }