Remove Websites Associated with my wpmudev account

Hi there,
I tried installing Snapshot on a website I'm working on, and the Install button was disabled and it said I needed a Dev subscription. How many websites can I use the WPMU dashboard on/install plugins from?
How do I remove websites associated with my wpmudev account? One website no longer exists so I can't login to it to remove the plugins. Is there a list somewhere I can view that says which websites are active/associated and which ones aren't?

If not, what do I need to do to be able to pick and choose which websites I want to use my subscription for? I'm not a full blown developer just yet.

Thank you!