FB has Activity Log, visible only to you, and shows what you posted, commented, liked, tagged, shared, searched, etc. From there you can manage and delete stuff if you want, by hand.
https://theconversation.com/shadow-profiles-facebook-knows-a...
I guess one way to avoid shadow profiles would be to block FB scripts/cookies on pages you visit, so they won't track you.
It's a black box for most of us. You might need to provide fake data to make it relearn. There were comments here and there about people liking various pages/posts not related to them, just to feed it with junk.
I don't even think it guarantees that new neural nets won't be trained on your 'deleted' data
That they are in essence keeping "the ghost" of a person is another thing.