The pad removal process in this guide is performed with the caliper off of the vehicle. The installation process is documented with it on the vehicle. Both procedures can be done with the caliper on the vehicle. The calipers were off of this car for cleaning, since the soft rubber hoses were being replaced too.
You'll need to remove your wheels to perform this work.
Start by removing the cotters from the pins that hold the pad retaining springs in place. Not all calipers will use cotters in the pins; some may use compression fit pins. See the front brake pad replacement guide to see how these are removed.