how to remove back seat from 2001 Cadillac Deville?

Slide bottom of bench seat back and upward to release clips (requires a lot of force)
Lift bench seat out
You will see bolts or clips holding the back of seat release/unbolt these and push stright up to release upper clips on back of seat to remove. 2001 Deville has two additonal bolts in the trunk that release the top of the seatback.
Push the catches on the front bottom edge of the rear seat cushion toward the rear of the car, and when they disingage, lift the front of the rear seat cushion up. You will find that the battery is also under the rear seat cushion, he catches are in about centered on each side... about halfway between the end of the seat and the center floorboard hump.
Move the FRONT SEATS all the way forward to get room to squat down, so you can put enough pressure on them to release them.
You can do one side at a time.there are some clips on the floor pointing up about half way between the hump and the side. The seat drops down into these clips and the seat is usually secure. By getting into the back seat foot well and using your knee for leverage while pressing down on the seat, it will push back far enough to release and you can then rotate it up or lift ist out. The seat seems loose enough to lift, It still needs to be pushed back and the catch released before you can lift the bottom cushion.

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How do you remove the rear subwoofer of a 2001 cadillac deville

This should help you.

Rear Window Shelf Trim Panel Replacement (With Sunshade)

1. Remove the rear seat back.
2. Remove the rear seat belt retractors.Remove the 2 push in retainers from the cross car beam.
3. Lift up on the front edge of the rear shelf panel in order to release the hook and loop material.
4. Lift up on the rear of the rear shelf panel in order to release the hook and loop material.
5. Lift shelf trim panel over the sunshade and remove.

1. Install the rear shelf into the vehicle.
2. Slide the rear shelf panel rearward with downward pressure in front of shade opening in order to engage the front lip of the shade housing. Ensure the rubber flap of the shade is above the rear window trim panel.
3. Pull the center seat belt through the slot in the trim panel.
4. Apply downward pressure along the rear of the shelf trim panel to engage the hook and loop material.
5. Seat the front of the rear shelf panel to the cross car beam.
6. Install the 2 push in retainers.
7. Install the rear seat belt retractors. Install the rear seat back.

Radio Rear Speaker Replacement

1. R
   
   
2. Remove the 4 retainers.
3. Partially remove the rear speaker from the rear shelf trim panel.
4. Disconnect the electrical connector.
5. Remove the rear speaker from the rear shelf carrier panel.

1. Connect the electrical connector.
2. Install the rear speaker into the opening in the rear shelf panel.
3. Install the 4 retainers.