1. You have a white board?
2. You have the proper pensils to write on them so you can erase it afterwards?
3. You have kids?
4. You have normal markers, which you should not use on the whiteboard?
5. Your kids think it is fun to use those evil non-erasable markers on your white board?

I have solution for you.

1. Take a white-board-erasable-marker.
2. Colour the non-white-board-erasable kids-generated lines over with that white-board-erasable-marker.
3. Erase all with some tissue, as you do with plain white-board-erasable-marked-lines.

Yes. It’s that simple.

Thank you Bart.