We’ve totally got deletion of systems on our list; there’s an old IC topic about it but it totally deserves an OOC one, too.
We will be doing this at some point, but it is a little complicated to implement. While it’s still in our backlog, you can always “reuse” a system by renaming and editing it.
Regardless of where you started creating a system, it’s available to be added to a cluster as long as it’s got a saved solution (done in Test mode). We’ll be improving the interface to make that more clear.
On the topic of accidental deletion, we’ll probably just pop up a verification dialog box with something like “Are you sure you want to delete this system?”
Thanks for bringing this up!