You don't have to wash it off. Many people do rinse the cleanser off with water, but you can also choose to gently wipe it off with just a washcloth or towel, especially if you have very sensitive skin that could use the extra moisture.
Directions for use without water: Apply a liberal amount of cleanser to the skin and rub gently. Remove excess with a soft cloth, leaving a thin film on the skin.Directions for use with water: Apply cleanser to the skin and rub gently. Rinse.
Hope this helps!