This article details one way hosts, alternative hosts, and co-hosts might deal with a meeting participant sharing inappropriate content or disrupting a meeting by sharing their screen. Go to Resolving Unexpected Behavior In Meetings for additional tips.
Stopping Participants' Screen Sharing
While a screen is being shared:
Click Participants in the bottom toolbar.
Hover over the participant’s name and click More.
Click Stop Video.
To disable screen sharing for all participants:
Go to your controls toolbar and click the up arrow icon next to Share Screen.
Click on Advanced Sharing Options.
Scroll to the Who can share section.
Select Host Only.