nop, once a user receives a note from a relay, there's no asking it back. so if I subscribe to you via relay A, and I receive your note, then when you issue your "delete" event to relay A, I already have your note, and if I then ignore your delete event, there's nothing you and relay A can do and I can send it to relay B that won't delete anything.
Discussion
Both scenarios do not contradicts my suggestion but are rather the risk anyone has right now also on Twitter.
Actually, in the first of your scenarios the data would be still on relay a when you view it. So it is not stored on your client if I am not mistaken. Deleting it, would still make it disappear, no?
clients can have their own db. they're not "automatically" synced with relays. twitter is different because it's just one client with one harcoded relay, so they control the whole experience on what to serve, but if someone screenshots the tweet, twitter can only try to remove those images, but the content is out there for anyone to see.