Soap (or better still baby shampoo) and warm water on an old flannel! As the paint is water based, it needs to be removed with water. Oily or cream based removers tend to seal the colour onto the skin. Baby wipes are tempting, but contain oils and are not designed for the face. People have said that olive oil, coconut oil and shaving cream have been effective at removing any staining left behind after thorough washing.