Unfortunately this feature isn't available currently in VideoScribe however we do have a task in the backlog to add an erase function meaning scribble out would be a thing of the past!
Here are a couple of workarounds within AfterEffects in the meantime though.If you are using darker colours for your drawn images and no hand on-top of a white background, I have found that making the layer a "multiply" layer in AfterEffects, this will make the white transparent and if the drawn images are dark enough they will still be strong enough to display properly.Another option is to cut up the rendered clip in AfterEffects, copying and reversing the section you wish to erase and dropping it into the timeline in the right place.
To take this further, you could have two versions of the image that you would want to erase, each one drawing from a different direction. One could be used for the "draw" and the other reversed for the erase. It being drawn from the other direction will stop it looking so much like its just been reversed.
No worries, while I took credit one of our design team gave me this fix so I'll pass your thanks onto Louis!