WD-40 your kids.
If you’re a parent, chances are you’ve found your kids with an ear-to-ear grin and a wall covered in crayon. What now? Do you scrub for hours? Do you re-paint? No. You WD-40. It removes virtually all evidence that your little one is a Bansky-in-training.
Try in a inconspicuous place first though – JUST IN CASE!