how to erase parts of painted canvas?

[Janet Reider]

I know there is a way to erase parts of a worked on canvas to expose the original.  I cannot recall how one does that... 

Please advise..

[Synthetik]

Here's a tip on erasing the canvas.

If you want to just erase part of the canvas, there are different approaches. You can select the parts of the canvas you want to erase, then turn on masking, and then run the main canvas erase option. Only the selected parts will erase.

You can also use an eraser paint preset. You can load that into the tip of your wacom pen, or use as the main working preset.