아래 메시지나 링크를 찾아가보시면 방법이 보일거같습니다
doridori2013@nate.com
Look into this GCM doc: GCM Unregistration
You should never unregister your app. This is taken care from server side.
When you send messages to GCM from your server you will get response string.In that if you are getting error as "NotRegistered, you should remove the registration ID from your server database because the application was uninstalled from the device or it does not have a broadcast receiver configured to receive com.google.android.c2dm.intent.RECEIVE intents."