The rear quarter headliners are actually separate pieces from the main overhead piece. You will only remove the small piece on the side by the driver.
1. Remove light assembly from headliner by using a small screwdriver to pry it up. It is held in with tension clips. Disconnect wiring harness.
2. There are 3 bolts that hold the headliner secure to the frame of the car. Remove these (one is hard to see.)
3. Slowly pull headliner out towards the front of the car.
Once you get the piece out, you will see the junction box mounted to the side of the car. You can either remove the antenna lead completely from the box and take the whole cable out, or just wrap up the antenna with a twist-tie and tuck it inside.
Reverse the procedure to re-attach the headliner. The most difficult part is getting the piece back into place properly. Be patient and go slowly and you won't have any problems. You may have to wiggle it back and forth a little to get it to slide back in.
Good luck.