on my kodiax 400 disc brake set up ,,,is this normal? or could my wife be riding them? or my friends? this is her bike ,its in inboard pad every time,now the brake disc is fryed.can they turn them?

 

If it's only one pad wearing down rapidly, you have a stuck slider on the caliper. So it doesn't sound like anybody is actually riding the brakes, the brakes are riding themselves. So that inboard pad will always be against the rotor, killing the pad and heating the rotor up and cooking it.

The job of the sliders is to allow the caliper to move from side to side and keep the pads centered on the rotor as they wear. If the sliders, which are basically a pin that slides in a channel, gets mud, water, and dirt in there, it'll get stuck and won't slide. You can try taking the caliper apart and cleaning the slider and channels out good and greasing them up, but sometimes they get so seized up that they won't even come apart, and you'll be stuck buying a new/used caliper.

About the fryed rotor, i don't think they can be turned, they're just too thin to afford any loss of material, and probably couldn't use the standard equipment to do it anyways.