Wash towels in hot water with a regular detergent
Add 1 cup of white vinegar to the rinse cycle
Rewash with 1/2 cup baking soda if the smell remains
Avoid using too much detergent
Skip fabric softener
Dry towels completely after every wash
Use the highest heat setting safe for the fabric
Remove towels from the washer promptly
Wash towels separately from other laundry
Clean the washing machine regularly
Leave towels unfolded while drying
Store towels only when fully dry
Use less towel per load so they can rinse well
Soak heavily musty towels in vinegar and water before washing
Replace towels that still smell after repeated washing