Deleting / Recreating a username?

I recently re-opened my account with Dreamhost and still had all my old usernames/e-mail addresses, and I wanted to wipe everything clean and start from scratch.

So I deleted everything from my panel including all usernames. Everything seems ok, but when I click on my groups tab, the old usernames still show up there as associatedd with a default group. When I try to recreate the user, I get an error message, not the usual user-friendly error that you’d get from the control panel, but the shell output from the script that’s trying to create the username, saying its already in the system.

Does it just take time for it to completely purge the username, or is it not possible to re-create a username after it’s been deleted?