To remove them, get on your back and under the car - you'll find some lovely bolts/allen screws that need removing (cannot remember which off top of my head, been a while since I did them) - 4 each side from what I remember.
They are difficult and awkward. You've got a tiny amount of space to work in and being located where they are - there is dirt around them.
I did WD40 on everything before starting.
I lost skin across the majority of my knuckles, I left most of is on the underside of my car, drew blood, swore worse than a sailor..........
Make sure you clean them up, give them a good base coat and then a few layers of paint - I used a heat resistant engine block spray paint on mine - nearly a can on each one, coat, dry, coat, dry - until the can had no more. Really because once they go back on, I've not zero intention of taking them back off again for any repair work.