My friend wants to remove modded Halo 4 unlocks

Hey, just need a quick answer for Halo 4.

A while back my friend gave himself all the armour unlocks in the game. He now wants to remove all the modded unlocks because he fears he may be banned when the game goes backwards compatible. How would he go about removing just the modded unlocks?

I suggested that if he were to removed ALL unlocks and then connected to Xbox Live, the game would sync with the unlocks he should have and fix it that way. Would that work? Or is he going to have to go through and individually remove all the modded unlocks?

Thanks in advance.

There is about a 0.01% chance he gets banned unless it carries into online. The only way he could go back to premodded is to have a copy of his save before it was modded or delete the save and start over.