@Anne-Marie152 do you have evidence that they stole it? If you do, you can make a claim through the resolution center although I doubt that the guests would want to recompensate anything and I don't know whether Airbnb will do something about it unless you can prove it. What did they stole?
@Anne-Marie152 use "send or receive money" and ask your guest to pay for missing towels. If you have a receipt for those towels then scan it and include in your claim, if not, find the same towels online and include the link to the webshop. if he declines or ignores it then involve Airbnb after 72 hours.
We have almost the cheapest white Ikea bath and kitchen towels and they still go missing from time to time. I hate when they do that and then deny.
I hope you still have the purchase tickets of the towels otherwise I'm afraid airbnb won't do anything, it's really difficult to get paid a part of the deposit from them when there is problems with the guests I find 😕