Not that I know of. Sierra won't be much help either, because they've all but stopped supporting the game.
I'd just change your password and give the new password to whoever you sell it to, along with instructions on how to change it and how to change their player name. I think you can change the email address too, so you might even be able to change it to their email address after the purchase (and after you verify it works) and it will resend a new password to them.