like 5 finger said. as long as your getting new rotors, because using a screw drive WILL fvck up the old rotor, in the top of the caliper is a slot, jam the flat head screw driver in between the disk and pad, then pry back and fourth, till the piston is all the way back inside the caliper. do this before you unbolt it.

should you find a C clamp, leave the pad on the piston, and then crank it back in with the C clamp.