ownership of content/ deleting a users posts
 

A while ago I had a user request me to delete his account, i duly did so but it left his username in place in posts/threads, all the content linked to it but his user account was gone.

He has now come back to me to request i delete all his messages, i can't find a way to do this as his account isn't there nor do i know whether he has any rights to request this, his user name is an alias and i'm unsure as to what rights he has.

Has this happened to anyone else and if so how do i solve it?

tia