If you are talking about the U-bolts holding the axle to the springs, cut those with a torch. It is not reccomended to reuse them.
If you are trying to remove the springs from the frame, then if it is a larger truck, one ton and up I think, it may have a small lock pin to remove, and then a big punch and a hammer will drive the large pivot pin out. Or a slide hammer with an adapter for the grease fitting hole works too. My 52 one ton is like this..
