You have to undo the bottom sliding bolt. 13mm. Then swing the caliper upward. Or undo the top one as well and take the whole thing off. The slides have a rubber boot and on the outside there is a bolt. If you take the whole thing do not hang the caliper by the brake line...but I am sure you knew that already

There may be a nut near the rubber which you may have to hold with a wrench while you undo the outside bolts.

Remember to remove your brake reservoir cap under the hood before pushing the piston back in.