Mods of sites sometimes delete tags.
When they do, what happens to old questions that had the tag? Is the tag automatically removed from all such questions?
What if a question only had that one tag? Is it left without tags?
You have this backwards, tags are deleted automatically around 24 hours after they have been removed from all questions.
What happens is that moderators or users remove the tag from all questions, not that they delete the tag. That way we can't end up with questions that have no tags.