How do you take out the rear seat in ford LTD convertible 1972?

The two holders Tennisshoes mentions are on the floor of the car, and are centred at the edge of each back footwell at the front of the seat cushion. Push in, fairly hard, on each one, and you will feel the clip disengage from the catch on the seat. Lift up on the front of the cushion once the clips have released, then pull the cushion towards you. Once that is out of the way, the bolts holding the seat back in place will be easily visible.

Thanks tennisshoes and Mike, now I managed to take out the seat! Peter

Putting the seat cushion back in can be a bit tricky. You have to push in on the bottom of the cushion and then down on the top of it, then release at the right time for the bar to catch. Once you've done it once it is simple, but you need to get a feel for it.