You have the power to decide who can and cannot chat in your room. If you go to "My Show Controls" in your broadcasting page, you will have a panel named "Who can chat".

There, you can make the chat available for everyone or restrict it to users who've bought tokens or subscriptions, or to registered users with verified emails. We recommend the latter in order to keep the activity in your room chat lively, but it’s completely up to you.

Note that if you turned on the option to hide Grey users’ messages, it will be automatically disabled the moment you set the chat only to “users who’ve bought tokens”.