At our app, we have 2 way to link PlayFab account to Facebook, when the app was opened for the first time and in settings at any time.
So we can have the next situation:
1) a user has been playing our game some time with Facebook
2) the user has removed our app
3) the user has reinstalled the game and played as a guest
4) the user has remembered that he/she had had progress in our app and logged in facebook (we relink new user id to old Facebook profile on PlayFab)
So can user remove this new guest account, when PlayFab has returned old Facebook account?