An awning is an exterior overhang on a building. They come in a variety of materials, from canvas to vinyl, and are susceptible to moss, lichen and mildew growth. The easiest way to remove lichen and dirt from the surface of an awning is with a pressure washer with a telescoping wand. If the lichen is particularly difficult to remove, you will need to scrub it off by hand.
Cover any nearby bushes or landscaping with plastic tarps to protect them from the bleach mixture.
Fill the reservoir of a pressure washer with equal parts bleach and water.
Extend the telescoping wand so it reaches the top of the awning. Turn on the pressure washer to medium pressure and spray down the entire surface of the awning. The bleach should kill any existing lichen and the pressure from the washer should remove it.
Climb a ladder and inspect the awning for any remaining lichen. If you find any, fill a bucket with the bleach mixture. Dip a nylon scrub brush into the mixture and scrub the lichen spots in a firm, circular motion until the lichen is gone.
Rinse the reservoir of the pressure washer and refill it with plain water. Set the washer to low pressure and rinse the awning. Let it dry in the sun.