how to close all rooms at a certain time

I'd like to close all game rooms (even though there are players in) at a certain time. For example, every monday 4:00am. It seems rooms have more garbages as time goes by. Because of program or network errors. So I thought I need to close all rooms to start it all over once in a while. I'm afraid if this is bad idea. How can I close all rooms at the same time? Any Photon commands for this? Or can I do this in the Photon homepage, not in the source codes? I'm using PUN and Unity3D. Thanks for any help.