Loosen the clamps, leave the pin in, soak them down with your favorite solution and use it. Keep a close eye on them, they will come loose. If time is not on your side then you will need heat and a hammer, or a jack between them, or tie one side off to a tree and put a come along on the other side and start heating and beating. Lots of different ways, just gotta do what you feel safe doing or have means to do.
Casey in SD