I'm not a dev, but AFAIK whether or not you can delete a note from a relay is a per-relay function. If a relay doesn't support that, then a delete command wouldn't do anything. Many clients do support hiding, but only on the client level. The relays are just databases - once an event is written, I don't think they make decisions on what events to "show" or "hide."

It's not a bug, it's a feature. If you can't force deletion of any of your notes across the system then we can hold you accountable for things you've said in the past. Think of it like being live on TV. Once you've said something it'll go out on the airwaves and then it's out there and not coming back. With nostr you're "live on TV" all the time.

The importance of keeping this protocol fully transparent is more important than deleting typos or minor mistakes. Say what you say and own it.