That’s the neat part.

Check out these FAQs. 🤙

https://thebullishbitcoiner.com/nostr-faqs/#2

in ametyst you can ask for editing or for deleting to relay owners.

Some relays accept it automatically

Try this https://nostr-delete.vercel.app/

Or on web you can delete with https://gleasonator.dev/

It is technically possible.

It is not likely that every relay will honor a delete request.

It's better to think about nostr being permanently transient in that many relays will not store older stuff (defined by their operator) so I think if it like an effervescent black hole.