How do i disable pregame & post game chat

I remember there was a way to disable pregame & postgame chat by blocking some of riot's ip adresses in the .hosts file on windows.

Does anyone have a guide/video/ Remember the ips that are requiered to block to disable pre/post game chat?

How do boosters play in offline mode? Does that disable pre/post game aswell?

And if it does how do i play in offline mode?