K/h caliper hanging up.

If the pistons are binding in the bores, you'll have to rebuild the calipers. If it's something else, like a plugged line or collapsed hose, you can crack the bleeder to release the pressure so the wheel will turn but it will bind up again the next time you apply the brakes. There is always a certain amount or residual pressure holding the pads against the rotors but it shouldn't be tight enough to where the rotor won't turn by hand.