I would just grab them and take them to the shelter. 
But you don’t have to live with him after you do that…so the dance has to be done. Over time.
Lol. Got it. I feel your pain.
My husband was cured of his hoarding habits when he (we) took a crapload of leftover building materials he saved over 18 years to the dump… literally a ton of crap. I am not kidding. I have a receipt that says how much the crap weighed.
Old towels are great for cleaning - rip them up
Do you already have old towels. My husband would keep every towel, too. How many are there of those particular towels? I would keep those and throw out others you are keeping. I think I have about 8 old towels. I have them In a separate storage area by the rags. That way if he says “where are those towels”, you can honestly say you have them. Just don’t offer you got rid of the 12 others that have been in storage for 20 years. Then get rid of what you want in a couple years when he’s forgot all about it.
We have instituted the “one in one out” rule. So, in our house, if we got 10 new towels, the ten old ones would have needed to go somewhere. If it’s to the rag bag, then ten old rag ones would need to be removed from the house.
We have a rag bin also. But once it’s full, nothing else goes in it. Nothing.
I keep a stack of old towels in the basement for those times when you need additional rags for cleanup or when surfaces need to be protected from some unusual project. I could never throw them out. I’m not a hoarder either. In fact, my husband accuses me of throwing things away we could use.
Old towels are a great donation to the local animal shelter.
D just cleared out the linen closet yesterday and I think she took out at least 15 bath towels. H wants to keep what’s left; I’m going to do some stealth discarding.
The dentkids and I are perfectly on board with the one in/one out rule. I use it for the girls and their clothing. Unfortunately, H cannot wrap his mind around this concept so he refuses to participate. He can get rid of almost nothing; I’m the opposite. He keeps e.v.e.r.y.t.h.i.n.g.
We have several piles of “old” towels/rags in different areas of our home. We don’t need to save anymore, though I may save these and donate some of the older ones. That was a good idea.
@dentmom4 could you post the link to the towels you bought?
Haven’t read all the posts.
I use dryer balls. They are about the size of tennis balls with nubs all over. They work. They are cheap. They last and last. Tennis balls will do almost the same. Three balls per load is great, two is good too.
@thumper1 https://www.macys.com/shop/bed-bath/bath-towels/Brand/Hotel%20Collection?id=16853. I bought the style that came in cherry pie. Looks like the sale is still going on.
Oh Macy’s will throw coupons at you if they don’t have a sale! Nice towels!! I need some for the guest bath… hmmm…