how to manage old installations

I'm giving pyapp a try for a new project. So far I like the simplicity, however how do you manage old installations. If I bump the version number I see that pyapp creates a new venv with that version number. Once I've overwritten the old binary I don't see an automated way to remove the old venv.  How do i manage old venv's without having to remember to remove them before updating the executable.  