How to Clean Wallpaper
Use a natural sponge lightly dampened with a solution of warm water and a small amount of liquid dishwashing detergent. Before cleaning, test the solution in an inconspicuous corner to be sure it won’t remove paper or coating. Don’t scrub too hard or allow the paper to get too wet to avoid damage. Always check the instructions first. This is for washable wallpaper.
Image from Wallpaper Warehouse