How to delete Postage Policy from Live listings

Until this evening, all my items were BIN with the same postage policy, which included Immediate Payment.  But then I wanted to create an Auction and wasn't allowed to use the postage policy because IP isn't allowed with auctions.

 

I tried to create a new policy but it kept saying I couldn't do that because of the live listings.  I've tried to delete the policy but it won't let me do that either.  So now I've had to edit the policy in order to get the Auction listed, but now it doesn't suit my BIN listings because it won't let me specify Immediate Payment.  I've tried to add IP to each of my BIN listings individually but it won't let me do that either.

 

I want to delete the policy altogether because it's now more trouble than it's worth, but how do I delete it when it applies to Live listings.  Do I really have to remove the listings in order to delete the policy?