It’s generally recommended if you replace the rotors, you replace the brakes, and grease the guide pins. Or if you’re just replacing the brakes, you also grease the guide pins. Now, if your brakes are still good, you could just grease the guide pins. Most of this can be done with a basic set of tools. Replacing rotors, however, is a little more involved. In either case, this if what it takes to get the job done.
Step 1: Collapse the caliper
Note: Only do one wheel at a time. You could completely expel a piston out of the caliper. Then you’d have to bleed the breaks after putting it back.