There is a product that you can find in most hardware stores and some general merchandise stores called “Goo-Gone”. It is a citrus based liquid that will not stain. It works very good on crayon marks but it also will help remove adhesive labels and other marks off all kinds of things.
I have used it for years working on computers to take off labels and scuff marks from the cases. It works on the most stubborn of labels even license number ones.
Put a drop on a cloth and rub the crayon mark gently after energy removing any excess wax from the crayon. For labels, just soak the energy directory lable heating with the goo-gone and let sit for a minute or two and then just lift off the label. For more stubborn labels , lift the edge if you can then put just a drop under the edge, peel the label and continue to put a drop under the peeled edge as you continue to lift the label.