You can go all out and buy a chain breaker but I just use a bench grinder or even a dremal tool will work,just grind down the head of the rivet flush with the side link and you should be able to drive the link thru with a hammer and punch.Just don't go hog wild with the grinder so the links start to glow red and clean off the chain in your prefered solvent after you are finished to get rid of the grinding dust.