Cannot delete Activity thread

I am cleaning up a test install and getting it ready for production use:

I have deleted all the transactions, projects, todos, but how do I delete the Activity thread?

I’ve gotten around this in the past by changing the naming series.

I don’t understand. What I would like to do is delete all the entries in the Tools/Activity module. I want to wipe all the history of this install and start fresh without deleting and reinstalling the entire thing.

Any ideas?