Since nobody said it- do the grind thing, but use a real tiny chisel to wedge/drive the side plate off of the link. You must grind the pins completely off as they are somewhat peened over like a rivet.
I have to do this on number 25 chain (no tool), which I then braise the pins back to the side plate after re-assembling them.
i find most of the peened over chains come out just as easy as the ones that arnt. And because of that i really hardly ever have to grind them. I think the trick is getting it positioned so that you can work it without mangling the chain. A bench vice is a must imo. Also rather than driving one pin all the way through. Which im under the impression some people do. Just drive both pins just enough to pop the side plate off.