You control the Highfive conference room device using either your computer or iPhone/iPad.
Computer: If you started the conference using your laptop, click on the Disable Camera button in the Highfive app. This will stop the device from sending conference room video to remote participants. Clicking the button again will re-enable the camera.
Mobile: If you started the conference on your iPhone/iPad, navigate to the Highfive app and tap anywhere on the main video screen to pull up additional menu options. Click on the Disable My Camera button: