OK, that all makes sense.
Thanks Mark
As far as I can see I can edit any note that was created, either public or private, but cannot edit a reply. That makes sense as a reply generates an email to the customer so editing it would create two versions of what was sent. As far a I can see this applies both to replies I sent, and replies other agents sent.
It is possible to edit a customer response, and we do use this, especially when a customer mail was sent to us outside FreshDesk and the mail was forwarded. We then change the sender and delete any details about the forwarding.
I can delete replies. I have had the problem that a reply was sent twice (at the same time, I think a problem with my mouse driver). Then I have deleted the second reply which is identical. However, the customer has probably received two emails.
So the me the available options make sense.