"message": "X-CSRF-Token request header is missing" When using postman to fire post request I get this message. Does anyone has idea how to disable it? In this case it is post to register user so no authentification is required.
This is not recommend to remove the X-CSRF-Token. Instead you should get the token from  /rest/session/token and add this token in your header with this value.

But if you want to disable it you can write this below line to your settings.php file  $conf['services_csrf_token_check_disabled'] = TRUE;