That's an option in your config file. <img src="https://www.ubbcentral.com/boards/images/graemlins/wink.gif" alt="" />
Look for this option:
Allow users that are not logged in to choose an unregistered username for their post
If that is set to "No" then all anonymous posts (posts by deleted users are anonymous) are set to "Anonymous". If that option is set to Yes, then the deleted user's old name should show there. <img src="https://www.ubbcentral.com/boards/images/graemlins/wink.gif" alt="" />
Although there's no way to search by username for a deleted user anyway. All user's have numbers - if you deleted that user - they get set to the anonymous placeholder user - user#1.
It's really not a good idea to delete banned users, as that gives them an easy opportuntity to regain access by reregistering. If their username is banned, then they are pretty much blocked from doing anything, but if you delete the user, then you also delete the ban. <img src="https://www.ubbcentral.com/boards/images/graemlins/wink.gif" alt="" />
But I think if you change your preference to allow the username to appear - then the username will appear. <img src="https://www.ubbcentral.com/boards/images/graemlins/wink.gif" alt="" />
