I'm pleased to announce that as of version 8.4.0, you can turn tracks on and off in Camtasia Studio. Turning a track off prevents auditory and visual content from appearing in the canvas, preview, or rendered video.
There are two ways you can turn tracks on or off:
Option #1: Click the eye icon to the left of the track. It acts as a toggle, so when a track is on, the icon is gray and the track is bright:
When a track is off, the icon is blue and the track is dim:
Option #2: Right-click on a track and select "Turn on track" or "Turn off track" from the contextual menu.