Taking the rear brake rotor off the spindle

I just have a general question in reference to taking the rear brake rotor off the spindle in order to replace the rear bearing hub assembly. There are screws holding the rotor on and I cannot get them loose-tried heat/chisel/PB blaster/impact driver/end punch nothing budged them. I need them off in order to remove the rotor to get to the assembly. My question is, how important are these screws since the rotor is held on by the caliper? Also, can I simply drill them out and not replace them?