Facebook Data Deletion Request Callback

I have a mobile application, we implemented a Facebook Login as one of the different ways to register and log users in, now Facebook asks for "Data Deletion Request Callback" which will delete Facebook data if the user removed the app from his Facebook account. the question is what data should I delete (Facebook ID, Image, Email)? or should I remove his account on my app (that will cause a problem with my data)? not sure how Facebook reviews, Approve or disapprove goes, can anyone share his experience about this?