Use a combination of bleach and water or vinegar and water. Put in a mister of sorts and spray liberaly on the area three or four times a day for several days. If using bleach, be careful about overspray.
When repainting, I would even prime the affected area just to be sure then go to Sherwin William's and get some mold/mildew retardant paint. This does work and you can get it in any color.