The caliper is held in place by 2 13mm bolts - with these undone the caliper body can be pulled clear and the pads withdrawn. They will be covered with all sorts of road muck and they'll need a thorough clean before you put them back. If you are renewing the pads, the piston will have to be turned clockwise as it is pressed in. A special tool is available for this.
John, August 2009