Yes, though I suppose you could just create another account. : )

You can stop a running instance by shutting down the OS. If it's something people really want we can add an API/UI mechanism to do it.

Huh, I did sudo shutdown now and it worked, but the gui says it's still running. So a button might be nice.

I've also tried 'sudo shutdown now' and while it did shut down the OS, the site says they are still running and the times are still increasing. How will I know when they've actually stopped? Also +1 for an API to end instances, please.