Wear a pair of latex gloves to protect your hands when cleaning the brick. In a small bucket, mix a cup of an oxygen bleach product, such as OxiClean, Ajax Oxygen Bleach Cleanser or Oxy-Boost, with a gallon of warm water. With your gloved hand, mix the oxygen bleach thoroughly with the water to dissolve the powder.
Pour the cleansing solution on the brick and allow it to soak in for about 20 minutes. Once the time has passed, scrub away the moss with a push broom or handheld bristle brush.
Rinse the cleaning solution off the bricks with a hose. Repeat the process, if desired, for old or stubborn moss growth. Clean the brick as needed for maintenance purposes.