There’s this to go by:
As you can see here, I only change the username to "Anonymous" on request.
There is barely anything archieved from the early profile ID numbers that lead to one of those "The user whose profile you are trying to view does not exist." Type messages. I did find one though: https://web.archive.org/web/20120326034624/https://bitcointalksearch.org/user/--407 (https://bitcointalksearch.org/user/--407).
It turns out to be @SyphirX’s account. That account is not accesible, but does preserve the username tied to his posts (for example here: https://bitcointalksearch.org/topic/bitcoin-classified-site-407). On this same thread there is a post by "Anonymous", which I figure relates to a requested to delete account as per the quote at the top of this post.