Thanks for getting in touch! That behavior certainly sounds incorrect and unexpected! I’m actually unable to reproduce this issue in my local instance running 2019.10.5, however. I was able to edit/delete project and common variable templates after deleting a tenant previously associated. Which version of Octopus are you currently running? If you’re easily able to reproduce this, would you be willing to send us screenshots or a screen recording of this issue? (ScreenToGif is a great free tool if needed.)
I look forward to hearing back and getting to the bottom of this one!