Finding Accounts on a client

[Hyperbole]

Hello, I think I stored a name a long time ago on one of my many accounts (I pretty much make a new account anytime I make a new toon) but I can't find it. I don't recall any other accounts I own but I may have missed one. I went into my clients files and I saw the toon's name so I know it was on this client/this computer.

Is there any way to see a list of usernames used on a titanium client, or am I shit out of luck? Password isn't a problem.