In the current implementation of the server, there is always an admin in a game. When the player count within a game reaches 0, it is automatically closed. This is ensured in the main game loop of the game thread. You could modify this to allow games to exist with zero players, however, you would need to rewrite the whole "administration" concept then.

Currently, the first player is automatically the admin, if he leaves the player who joined next will become admin.