White out is a generic name for Wite-Out and other brands of white correction fluid. The fluid dries quickly on solid surfaces, such as walls. Correction fluid may be water-based or oil-based, according to wite-out.com, and this impacts which cleaning methods will be most useful. The key is to start with the least aggressive method to try to prevent damage to the wall.
Scrape the white out with the edge of a thin coin, such as a dime or a penny. A coin's blunt edges help prevent scratching the wall--you may use any scraping tool, however, as long as you are careful. Get as much of the white out off as you can using this method.
Dip a cotton ball, for small spills, or a sponge, for larger areas of white-out, in warm water. Apply a drop of liquid soap to the cotton ball or sponge.
Wipe the cotton ball or sponge over the white out. Water-based formulas should start dissolving and transferring to the cotton ball or sponge. If this does not occur, then you are probably dealing with an oil-based fluid.
Spray a citrus-based cleaner on a paper towel to remove oil-based white out. Rub this paper towel over the area, keeping the movement confined to the stain so you don't spread the white-out over the wall or damage painted surfaces.
Dampen a paper towel in clean water. Rinse the cleaning residue from the wall by wiping it with the towel.