OceanSlim on Nostr: You have a relay list. When you make a post it goes to all those relay. What happens ...

You have a relay list. When you make a post it goes to all those relay. What happens on those relays is up to the relay operator... For instance that relay may be sending to other relays. Now, I'll link it below but a delete event is a kind 5 event that reference another event to delete. Whether or not the relay you're sending to supports kind 5 is totally up to the relay. Delete is optional for relays. But from my experience it's widely supported. There is no guarantee of delete on nostr.

No, your notes don't delete when you login/out.

https://github.com/nostr-protocol/nips/blob/master/09.md