The rear caliper on this Ultra is a Harley Brembo, four piston caliper. This is an excellent, high quality, performance caliper. There is no disassembly needed to service or inspect this area of your Ultra, unless pads are to be replaced.
With compressed air and safety glasses, blow out the Harley Brembo caliper body and brake pads. Remove as much dust as possible from this area without introducing any chemicals or solvents that may contaminate your brake pads. While doing so, it is important to inspect your inner and outer pads. Inspect how your pads are wearing. They should be wearing evenly. If they are not, it may be an indication of a warped, or scored rotor.
Wipe off both sides of your rotor with a clean shop towel and brake cleaner. Get a good look/feel while wiping the rotor. Now is an ideal time to take an extra minute for inspection. Make sure you do not see or feel any gouging, scoring, or warping/cupping. Remember; inspection plays an important role in basic maintenance.
Knowing how to correctly inspect areas/components on your motorcycle is just as important as correctly installing them. Catching a problem during a routine inspection may save your life. Therefore, inspection is not something to just breeze through, or be taken lightly.