The best way is to use the solution of bleach and hot water. While doing this make sure that you may use gloves and mask for safety purpose. In future your wall must be well plastered and painted, so that wall does not got wet and hence no mold will form in future. mold damage repair great neck - http://www.flooddamagecleanuplongisland.com/
You can try getting rid of mold on walls by spraying white vinegar onto the mold. Wash and rinse the area. Make sure it dries well. If this doesn't work, or the mold is through the paint to the drywall, you will need to remove and replace the drywall.