Topical Areas: unable to remove old, no longer in-use topical areas

[kyletcook]

When user wants to remove an old topical area that is no longer in-use, or renamed, or replaced, this can be blocked. Currently, in order to remove a topical area it can't have any events tied to it in the calendar. So, a topical area that was widely used a few years ago, is unable to be deleted without removing the tag from each of the events, or deleting all of these events.

This has caused trouble moving forward, since old topical areas clutter up the admin interface. Making name changes to a topical area requires complete replacement.

Would like to be able to update topical areas add/remove without having to prune its ties to past events.