I recently received an inquiry from Nick, a high school student:

"It would be very helpful to add an action button that erases all traces. Erasing traces should be available to non-GSP users and additionally, it would save the user the time of having to manually erase all traces in the menu. It is a pain to do so every time. Thanks for considering my suggestion."

In fact, you can already do this without too much trouble, by using a Presentation button. The properties for a presentation button include "Before starting: Erase any traces."

The only hitch is that to make a Presentation button, you must have another button to present. What I usually do is to make a Show button that shows some object that is always visible in the sketch. (I set the Show button properties to "Always show objects.") Then with the Show button selected, I create a Presentation button, set its properties to include "Erase any traces," and change its name to "Erase Traces."