1. While others are screen sharing, you can click the X in the bottom left of their window to stop their screen sharing. 

Alternate way to remove someone's screen

  • From the interactive touch display, tap the Collage button.
    1. This button is floating, it can be moved around the screen
  • Tap View the Device List > 
  • A window will appear with the list of connected devices
  • Tap the power button by the device you want to remove