SOAK THEM IN VINEGAR
Get a bucket filled halfway up with water then pour 2-3 cups of vinegar into it. Now soak the towels inside the bucket for 1 hour. After doing that you can either rinse them normally (inside the washer ) or you can do it with your hands. Then dry them.
WASH THEM WITH OXI CLEAN
Throw the towels into the washer and add 5 scoops of oxi clean into the washer. This will make your towels really clean. Remember to use fabric softener to make the towels smell better.
CLEAN THEM WITH BORAX
Put the towels into the washer then pour 4 cups of borax into it, and some fabric softener as well. Now turn on the washer. After washing them you can either air dry them or just use the dryer.