There are a few things you can do to clean a stain from a brush. The first is to use a mild soap and water to clean the brush. This will remove any dirt, oil, and other debris that may have been on the brush. Next, use a dry cloth to clean the area where the stain was located. Be sure to avoid getting any of the cleaning solution on your skin or clothing. Finally, dry the area completely and store the brush in an airtight container for future use.