To remove the front hubs. All you have to do is. Back the 4 bolts out about 1/4". Put a socket and extention on one bolt. Now smack the end of the extention with a hammer a few times. Move on the next bolt. The hub will pop out.
For the rear hubs. Remove the axle nut. Next, remove the 4 bolts in the back of the hub. It's a tight fit in the back of the kuckle. It's best to use a 1/2" drive thin wall socket if you have one. Or use a 3/8" drive socket.