Mix 1 tablespoon of apple cider vinegar with 4 cups of water in a spray bottle. Pure spring water is best, but tap water is fine as long as the water is not hard or contaminated. If you only have hard water, purchase some distilled or spring water from your local grocery store.
Spray the leaves and soil of the plant with the solution until the leaves and soil are visibly damp. Be careful not to over-dampen the soil with the solution because increasing the moisture content may cause the mold problem to grow worse, not better.
Gently blot away the mold with a paper towel if it begins sloughing off the plant. If you don't remove the mold, it may recur or it may rot and develop a foul odor.