A Presenter has the ability to stop all other broadcasts in a room should they need to.
Here's how to stop all other broadcasts:
While another Participant is broadcasting, navigate to the Participants menu.
Click on the three dots (...) at the top-right corner of the panel,
Click on the Stop other broadcasts option. A pop-up box will come up asking you to confirm if you would like to stop other broadcasts.
Note: stopping broadcasts does not revoke other participants' permission or ability to broadcast.