How to Turn Crossplay Off in MW2 on Xbox
You cannot turn crossplay off in MW2 via the game. Hence, you need to go into Xbox settings. So let’s start the process
Go to dashboard, and press the Xbox button and select settings
Now, go to Online safety & family from the General tab.
Then go into Privacy and Online Safety
Select Xbox Live privacy.
Then click View Details and Customise
Next, select Communication and Multiplayer
Under Communication & multiplayer look at the "You can play with people outside Xbox Live"
select Block for turning off the crossplay in mw2