K.A.
Skip the fabric softener on towels. It builds up and makes them not as absorbent. I wouldn't recommend it for any clothes at all personally.
First thing I would recommend is to wash them without any detergent etc in the wash and put white vinegar in. If you have a top loader put a cup right in, if you have a front loader put it in the fabric softener dispenser. Wash them in the hottest water you have.
If you see suds in the machine without having added detergent, wash them again until you get clear water. Then dry them. Get several tennis balls and throw them in the dryer. Do not use dryer sheets or anything else in the dryer.
From that point on wash them in hot water with at least half the detergent that is called for and white vinegar in the load and never use fabric softener or dryer sheets on them.