nostr:npub1k3dv5zwuuk5a3tee7kc3ducxhfdeeut4649enmmlu393fctkmlhqeck7dv is right, there’s no way to know for sure that a relay will honor the delete request. This is the same with centralized services. We could make some sort of check to make sure relays stop sharing content that the author requested be deleted, but that doesn’t exist yet. Still I think this is much better than systems where delete is impossible, like scuttlebutt.