2002 Pontiac Grand Prix Rotors

I have done both front and rear brakes before but have never come across thir. I was trying to get the rear rotors off but couldnt. The emergency brake was off, Caliper off, even the e brake spring. It seemed like the top of the rotor was loose but the bottom wasnt. I could rotate the hub but it was always tight on the bottom of the rotor. Help please