You can either cut off the cable at each caliper, or just grab the ends with a strong plier and pull them off the levers. Either way will work. Just not a good idea to keep driving the car with the rear brakes dragging.
BTW, you can drive the car for some time with the e brake cables detached as long as you are not parking on a graded surface. I've been doing it for a couple of weeks and if it's too cold this weekend, I'll put it off another week.
When you do get it fixed, you will want to look at the condition of the rear rotors and pads. If this has been going on for awhile, they might have taken some severe wear.
