You need: 1 cup of vinegar, 1/2 cup of baking soda and hot water.

1. Set your washing machine to have very hot water. Wash the towels by adding the cup of vinegar.
2. Once the wash cycle is finished, leave the towels in the washer, add 1/2 cup of baking soda and do another wash with hot water.
3. Once complete, use the spin cycle and dry as you normally do