Is there a command to delete all posts ever made by a particular user?

Admin -> Delete posts from a user

Then there are 2 choices. One to leave a "post deleted by tag" if there are replies, and the other will essentially delete the user and any replies to thier posts (that can end up deleting other people's posts)

OK But I screwed up. LOL I have already delted the user. Now his posts still have his name on them and it says "username not found". Is there anything I can do to get rid of all his posts short of looking thru every single thread and deleting them?

Not really - trying to delete them directly with a query would cause some serious problems, as several other tables have to be updated when a post is deleted, and you can't break the "thread" of a forum, so any replies need to be dealt with as well.

You would end up with a situation where random threads and forums would simply no longer appear as the JOINs wouldn't work right.

The scripts to delete a post are pretty complex as they have to deal with a variety of sitiations without breaking anything.

Hmmm...

I host your site for you and have an idea. Going to send you a PM.