Alright. I tried it for one and it deleted it, then the other has no topics marked with that tag and it's still there.
GuideHelpThreads-I had 10 threads marked with it and deleted them, so that tag is gone.
GroupRP- I had 18 threads marked with it and deleted it from all 18, and that tag is still there.
GuideHelpThreads was the last one I did, and the one that deleted, so I wondered if it was because it was the most recent one created.