sometime its necessary to stop or unregister notification services in your app like from your setting screen then you can use these codes.

you have to create a static handler in your gcm register class

static Handler myHandler;

and in your particular activity'oncreate method

myHandler = new Handler()
    {
        public void handleMessage(android.os.Message sendMsg) 
        {
            super.handleMessage(sendMsg);
            if (sendMsg.what == 0)
            {
                GCMRegistrar.unregister(context);
            }
        }
    };

now obtain message for this handler and tell your gcm register class that you want to stop that gcm service like this

        Message msg=MainActivity.mHandler.obtainMessage();
        msg.what=0;
        MainActivity.mHandler.sendMessage(msg);