Generally, you pull off the dust cap (please don't use channel locks) remove the cotter pin, remove the nut and washer and outer bearing.

Reinstall the nut and pull the rotor off, hook the inner bearing on the nut and give a sharp pull. That should remove the seal on the back side of the rotor and leave the seal and inner bearing on the spindle.

Remove all the grease, the old grease will do you no good at all, clean all the parts, inspect for damage. Inspection is visual and mechanical, you look for any marks, dents, flaking, then rotate the bearing with your hand feeling for rough spots. I use lacquer thinner to clean, it is very fast, but mineral spirits works good too. You don't want to soak the seal in solvent. I spray with carb cleaner to give a final clean. Repack the bearings and reinstall. The seal can be reused in most cases.

You tighten the nut while spinning the rotor, it will stop spinning when you get tight, back off from there, you don't want much play, but too little will burn up the bearing. Mechanics have a feel for it, it's only a few thousandths of an inch. Put on the lock and pin, err on the loose side when putting in the cotter pin.

There is no need for all the packed in grease inside the hub, it's there only because the factory is lazy and grease is cheap.