Firstly try removing any remaining dust or dirt without any cleaning product. Help yourself with a brush or, if needed, a vacuum. You will be surprised to see how much you will clean it with just a dry clean - up
If your product has a greasy or liquid stain, try cleaning it with a damp cloth. If the staining remains, add a bit of white soap in it and gently rinse it.
The key is, after you rinse the furniture with water and soap, to leave it drying outdoors. The more direct sunlight it has, the better. Even though Sunbrella´s upholstery is water, UV rays and mold resistant, it is essential to let it dry naturally. Do not worry, the upholstery will not fade or leave a mark after you wash it.
Never use detergents or abrasive cleaners.