How do I make the asker understand that edits that change the whole question are not allowed? Can someone please roll it back for me? [duplicate]

I recently answereda question about Tkinter, and the OP accepted the answer. I don't think the OP understands SO's system. I know I can roll it back to one of the good revisions, but I don't have enough reputation to.

Can someone please roll it back for me?

And what is the best way to make the OP understand why edits that change the question completely are not allowed? (because the thread as a whole will look senseless, won't help future readers etc.) Should I leave a comment or just let it be after the rollback?

I've seen:

1. How to handle an OP's edit that changes the question
2. Dealing with questions that are edited after my answer has been accepted
3. Should a question edit be rolled back if it appears to be a follow-up to an answer?