How do you Remove the front break rotor on an 1989 4x4 bronco II?

you remove the caliper then you use a magnet to pull out the pin in the retaining nut on the spindle then you unscrew the reataining nut and your done

Well, that's a rather brief and unsatisfying answer for a fairly lengthy procedure. If you are tackling a 4x4 rotor removal for the first time, I would strongly recommend investing in the Haynes manual. There are quite a few steps and some require detailed explanation. Plus, the drawings help a lot, especially the exploded ones, if you forget the part order. Also, the answer will vary somewhat, and requires a locknut tool, if you have manual hubs.