Nope - notes are forever
*kind of - there is a technical way that some relays can implement something writing over a note or forgetting it, but we aren’t there yet (someone technically smart will have to explain more)
Discussion
I believe it would only be removed from those relays, if I’m understanding correctly. Where the Internet actually does forget, nostr does not.
Its not over-writing, but as I understand it, some clients can send a 2nd note saying, effectively, 'ignore the 1st note'. No guarantee that relays or client progs respect that, though.
Even if every relay you posted to “deletes” the note, you still have to trust that they actually did. At the same time, even if your relays did delete the note, someone else might have broadcast it to other relays you aren’t using so you never know where it could end up. Point is, there is no guarantee of deletion.