remove alias using google php api - alias

Question

Is it possible to remove a user's alias using a service account and the google php api?
I have tried several methods, including:
$optParams = array('alias'=>$userMail);
$remove_alias = $directory_service->users->delete($user_info['primaryEmail'],$optParams);
$remove1 = $directory_service->getAuth()->authenticatedRequest($remove_alias);
AND
$url = "https://www.googleapis.com/admin/directory/v1/users/" . $user_info['primaryEmail'] . "/aliases/" . $userMail;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$request_headers = array();
$request_headers['Content-type'] = 'application/json';
curl_setopt($ch, CURLINFO_HEADER_OUT, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "DELETE");
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
$output = curl_exec($ch);
$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$header = substr($output, 0, $header_size);
$body = substr($output, $header_size);
curl_close($ch);
I get either error 401, Login Required. Or error, unidentified 'alias'

Answer 1

It looks like calling users->delete vs users_aliases->delete might be causing the issue. Maybe something like this would work?
require_once $CLIENT_API_PATH . '/vendor/autoload.php';
date_default_timezone_set('America/Los_Angeles');
// this is the service account json file used to make api calls within the domain
$serviceAccount = $JSON_PATH . '/service-account-creds.json';
// delegate the work to an account with ability to make changes
$impersonateUser = 'adminWithRolesToMakeChanges#your.domain.com';
// these are the scope(s) used.
define('SCOPES', implode(' ', array( Google_Service_Directory::ADMIN_DIRECTORY_USER_ALIAS ) ));
putenv('GOOGLE_APPLICATION_CREDENTIALS=' . $serviceAccount );
$client = new Google_Client();
// loads the json service account file.
$client->useApplicationDefaultCredentials();
$client->setScopes(SCOPES);
$client->setSubject($impersonateUser);
$dirObj = new Google_Service_Directory($client);
// This is the user account to delete the alias from
$userKey = 'joeschmo#your.domain.com';
$alias = 'alias2delete#your.domain.com';
$aliasObj = new Google_Service_Directory_Alias( array( 'alias' => $alias ) );
// delete the alias from the account.
$results = $dirObj->users_aliases->delete($userKey, $aliasObj);
// If successful, this method returns an empty response body.
print_r($results);
See Also:
https://developers.google.com/admin-sdk/directory/v1/reference/users/aliases/delete