iPadOS 16.1 Mail multi-windows - how do you close them?

I just upgraded my iPad Pro 11" 3rd gen (M1) to iPadOS 16.1. I was hoping the multi window system would be more obvious, but still stumbling around in it.

Anyway, my question is about the new Mail multi windows. I see you just tap + and it creates more Mail windows. But how do you close extra Mail windows? If I chose close from the … at top it closes the whole app.