Deleted posts still appear in the "last post"
 

I had this bot come in and post a thread in every forum. So I deleted all of the threads by that user in the Admin CP but when I come back to the main forum all of the posts still show up in the "Last Post" of the index page.

Can someone assist me with this?
Thanks

Could you tell me the steps you took to delete the posts?

Well in the Admin CP I searched for the user who made all these threads, selected delete user, then I chose to prune all his posts, then I deleted the user.

Thanks