Do you have full size Montero or Montero Sport? I can't tell you about Sport, but on the '01 full size Montero rotors come off without having to disassemble the hubs.
For the front brakes you'll need to remove the caliper (2 bolts) then the bracket holding the pads (2 more bolts). You have to remove the the bracket in order to remove the rotor (not enough clearance otherwise). Then look for a small screw on the inside part of the rotor (i believe it is a philips head). It might be rusted up and hard to remove. If you can't remove it - drill it out. If rotor does not come off easily at this point, use two bolts of the same size (metric, possibly 6(?)mm). Screw them into the two holes on the rotor. Work both bolts evenly and try to dislodge the rotor from the hub. If this is the first time rotor is coming off, it can be tough. Rotor can be pretty well "attached" to the wheel hub by rust and dirt. But it will pop off eventually.
Rear rotors are similar to this, but you do not need to remove the bracket, just the caliper.
What is the reason for you wanting to turn the rotors? Are they warped? If so, turning rotors may not be worth the effort. I had a warped rotor and had it turned in the shop. The brake pulsation came back shortly after. Apparently the rotor got heat stressed and was continuing to warp in the same spot again and again. I went ahead and replaced all rotors with the new PowerStop kit from RockAuto Parts Catalog
. The kit has new rotors and pads (part #K2755) These work beautifully and my Monty stops like a dream. I hope this helps. Good luck.