Before buying new I will try to cut them first.
Warped- track used.
How much are new? - for the future.

 

To remove the rotor you:
1) Unbolt the caliper, there are two bolts per caliper
2) remove the caliper
3) pull off the rotor

Its pretty easy to do.
I'm not sure how much new rotors are.

 

1.Remove the wheels. Remove the two pins holding the pads/retainer on each caliper(use a mallet and a drift tool for the pins).
2. Slide out the brake pads. Don't forget to buy a piston retractor to push your pistons back and might as well change your brake pads.
3. Clean all parts before re-assembly. Make sure you got all the parts(rotors and pads etc. ready).
4. Do the same steps on all the remaining brakes assuming your gonna change all for corners. Goodluck!

 

BTW, Next step is given by Yogi B.

 

You don't have to remove the pads if you dont want to, I never do.
But you might have to push the pistons back into the caliper with a pad retractor, I always do, it makes putting the caliper back on easier.

 

Thank you

 

What kind of tool I need to unbolt a caliper?
I want to be ready before taking it apart.
Thanks

 

To unbolt a caliper all you need is a 19mm socket with a wrench (or 19mm spanner if you want).
I find it helps to jack the whole front of the car up so you can pull the wheel over to make more room to work with as it gets a bit cramped down there.