Hang the towels outdoors to air-dry if they remain wet. Sunlight alone kills the majority of mold spores in towels.
Launder just three moldy towels at once with 2 tbsp. of baking soda and 1/4-cup of laundry detergent. Use hot water to fully kill the mold. Washing three towels per load ensures they each receive thorough cleaning.
Let the towels complete the washing cycle. Once the rinse cycle approaches, add 2 tbsp. of baking soda to the towels. Baking soda destroys musty odors.
Run the laundry through another rinse cycle once all cycles are complete. Rinsing the towels twice removes all baking soda and detergent buildup.
Dry the laundered towels immediately to prevent mold from breeding in them. Use your dryer's hottest heat setting throughout the drying cycle.