First, you need to use a leaf blower. Use it to remove some lighter and larger objects, Hold it and sweep your lawn.
Second, Flush the fake grass with a water pipe. Gently rinse the surface of the lawn with water, So we don’t need so many waters.
Third, Use a paper towel to gently wipe the more visible stains. If some stains are difficult to remove. Such as dog faeces or urine, we can use particulate detergent and other items to remove these stains. Finally, clean them with water. More details you can check this article.