Unable to remove label in GMAIL PHP API

Question

I am working on a project where I have several labels associated with every email. I want to remove the labels using gmail PHP API. I have followed the documentation and I have done all the steps. But, I do not know why I get Error, when I try to remove the label.

This is the code that is associated with the project. Please help me with any thoughts.

  $client_id = '[email protected]';
  $service_account_name = 'anthony@teak-truck- 130612.iam.gserviceaccount.com';
  $key_file_location = 'anthony.p12';
  $userid_from='[email protected]';
  $client = new Google_Client();
  var_dump($client);
  $client->setScopes(array('https://www.googleapis.com/auth/gmail.modify'));
  $client->setApplicationName("Client_Library_Examples");
  if (isset($_SESSION['service_token'])) {
    $client->setAccessToken($_SESSION['service_token']);
 }
 $key = file_get_contents($key_file_location);
 $cred = new Google_Auth_AssertionCredentials(
  $service_account_name,
  array(
 /*     
    'https://www.googleapis.com/auth/gmail.send',
    'https://www.googleapis.com/auth/gmail.compose',
    'https://www.googleapis.com/auth/gmail.modify',
*/
    'https://www.googleapis.com/auth/gmail.readonly'
 ),
   $key
   );
   //var_dump($cred);
  $cred->sub=$userid_from; //<-- Important!
  $client->setAssertionCredentials($cred);

  if ($client->getAuth()->isAccessTokenExpired()) {
  $client->getAuth()->refreshTokenWithAssertion($cred);
 }
 $service = new Google_Service_Gmail($client);
 $messageId=$_REQUEST["id"];
 $userId = 'me';
 $optParamsGet = [];
 $optParamsGet['format'] = 'full';
 $message = $service->users_messages->get('me',$messageId,$optParamsGet);
 $labelsToRemove=$_REQUEST['label'];
 $labelsToAdd=[];
 $message=modifyMessage($service,$userId, $messageId, $labelsToAdd,         $labelsToRemove);



    function modifyMessage($service, $userId, $messageId, $labelsToAdd,  $labelsToRemove) {
     $mods = new Google_Service_Gmail_ModifyMessageRequest();
     $mods->setAddLabelIds($labelsToAdd);
     $mods->setRemoveLabelIds($labelsToRemove);
    try {
     $message = $service->users_messages->modify($userId, $messageId, $mods);
     print 'Message with ID: ' . $messageId . ' successfully modified.';
     return $message;
    } catch (Exception $e) {
     print 'An error occurred: ' . $e->getMessage();
   }
 }

Answer 1

As given in Standard Error Responses for Google APIs, 403: insufficientPermissions error code means that the authenticated user does not have sufficient permissions to execute this request.

To delete labels, you should have this scope code in your permissions:

https://www.googleapis.com/auth/gmail.labels

For more details about scopes, please go through Choose Auth Scopes.