Crayon marks on unfinished wood may seem impossible to remove. Wood is pretty porous and crayon wax will sink into the wood's pores. With just a little work, you can get rid of the crayon and return the wood to its original beauty. You don't need harsh cleaners or toxic chemicals to perform this job, so you can avoid leaving stains on the unfinished wood.
Gently scrape the crayon mark with a plastic scraper, a putty knife or a butter knife. Hold your scraper at an angle to keep damage to the wood at a minimum. You should be able to remove most of the crayon this way, but some color will remain.
Wear leather or cloth work gloves to protect your hands. Hand sand the crayon-marked areas with fine sand paper (about 150 grit). Don't press hard. Just lightly go back and forth over the area with the sandpaper.
Wipe off any wood-dust with a soft, dry cloth. If any crayon color remains on the wood, simply sand it some more until it disappears. When you have finished, the sanded area might look a little lighter than surrounding areas of wood. Lightly sand around the borders of the area to blend the wood shades together.