To prevent participants from screen sharing during your meeting, use the host controls in the bottom toolbar. Click the arrow next to Share Screen and then Advanced Sharing Options.
Under “Who can share?” choose “Only Host” and close the window. You can also lock the Screen Share by default for all your meetings in your settings on ConferZoom.org (see the topic: My ConferZoom meetings inside Canvas are asking for a password)
Click on screenshot below to view the full-size image: