You can remove the pad with the dash frame in the car but your better off removing the entire assembly. Remove the kick panels. Disconnect the bulkhead connectors, steering column wires, blower motor wires and door jam switch wires. Drop the steering column down and removed the two studs. Remove the four bolts at the base of the windshield. The only thing holding the dash assembly in the car is a bolt on either side, behind where the kick panel were.
This seems like a lot of work but it isn't. You can set the assembly upside down on a bench and get to all the dash pad nuts. You will have to remove the light bar to get to a few of them. Doing it this way will save you a lot of time. It can be done in the car but it will take you a lot more time. If you are installing an aftermarket pad, it will need some trimming. It would be easier to do on a bench.