you can grind the pins on the link you want to remove, or go to a bike shop and get a chain tool to press the pins out, they cost anywhere from $7-$20 depending on which type you buy. the nice thing about having this tool is..... if you make a mistake and cut your chain too short, you can add a link.
when putting your master link back on, remember this.
its extremely important that you put the locking clip on so that the rounded end faces the direction of chain travel. if you dont, and the chain rubs on something like a tensioner or roller, the clip will be pushed off leaving you stranded.