Board Thread:Support Requests - Getting Technical/@comment-5907266-20150726191142/@comment-24930713-20150727083840

I'm not sure, but it sounds like if the category is being added to the forums in general, then the category will remain until all instances of the template being used are removed from the forum. I can't be of more help than this, though I suggest telling your users to notify you or another admin of problem threads/posts instead of using the delete template.