Manage site permissions

I gave my site `ADMIN` permission and now I would like to revoke it. How can I do that ? I haven't found a command to do it...

The issue names no file, command entry point, or test. First inspect how site ADMIN permissions are granted and whether revocation is supported; done means providing a clear way to revoke that permission and documenting or validating the behavior.

索引モデルが issue の本文から書いたものです。