Bleach does kill moss. However, bleach kills other plants, such as grass and flowers, and can discolor pavement. Bleach diluted in water is less likely to kill surrounding plants or discolor pavement.
To kill moss using bleach, combine 20 ounces of bleach with 5 gallons of water. Using a sprayer, soak the affected areas with the bleach solution. After approximately 15 minutes, rinse off the area with warm water. After a few hours, the moss turns yellow. Then, scrub off the yellowed moss and rinse the affected area again. Bleach prevents the moss from growing back for years. Direct sunlight prevents moss from growing, so cutting tree or shrub branches increases sun exposure to affected areas.