Searching in the web and in Stack Overflow I didn't find post where the problem was solved
I've this code
$params = array();
$file = new Google_Service_Drive_DriveFile();
$file->setProperties("myProp"=>null);
$response = $driveService->files->update($fileid,$file,$params);
and has no effect... the property mantains its original value (set with the same method)
In this case, how about using Google_Model::NULL_VALUE
? When this is reflected in your script, it becomes as follows.
$file->setProperties("myProp"=>null);
For properties
$file->setProperties(['myProp'=>Google_Model::NULL_VALUE]);
For appProperties
$file->setAppProperties(['myProp'=>Google_Model::NULL_VALUE]);