It's a good idea to do this on a level surface or chock a wheel so the car does not roll. Or have someone hold the regular brake. In other words: be careful.
Release the handbrake. Put it all the way down.
The handbrake cable to the brake assembly is visible when you look in the wheel well to the front of the tire (tyre). Put your hand on it and follow it to the point where it ends. This is the actuator arm for the safety brake at the caliper.
Apply force, with your hand, to push the arm towards the rear of the vehicle.
The arm should move, usually with a "click" and the brake will be free.
At least that's what I have been doing on my '90 until I can spend some time really fixing it. The article referenced in another response is very good.
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