sdr nailed it. The release is crucial and it is basically one of the final steps. You want a full lien release. Different lenders react in different ways. Like I said in another thread USAA was not gonna play. I found Wells Fargo to be okay at least in my dealings with them and they issued full lien releases. In other cases I have seen other lenders not issue a full release and basically convert the unpaid balance into an unsecured loan.
Again this is usually towards the end. Get to that point first and then if they do not issue the full lien release work with them to get it.