I was told accounts will never be deleted. Even if they are deleted, that username is still seen in people's "Quotes". I remember a user named Pollygone had constantly requested her account be deleted. The Mods/Admins would not do so, and she just ended up getting banned.
tl;dr I believe accounts will NEVER be deleted.
We don't delete accounts. Ever.
And it's very very rare cases where we'll perma ban an account. People are going to be able to google you regardless. Any quotes people have made of your posts don't get delete and keep your old username on them even if you change it. And there isn't any way we can change that.
If you would like to leave you are more than welcome to leave, but we aren't going to do anything to your account.
Juba did say he might do it as a payed service if a member has below x posts and hasn't been on in x days