I really do not know about your car, but usually you remove the bottom, then you can see how the back is secured.

To remove the bottom, try pushing the very bottom of the seat toward the rear of the car while lifting up on it. Often you have to do this on both sides of the seat, one side at a time.

Often a portion of the wire frame of the seat sits in a clip which is held in place by some spring pressure built into the seat wire frame.

In my experience, the clip may be double ended, and if you push too hard, the clip will hold in the opposite direction.

The clips that I have seen look like a small dome with an inverted T-shaped slot cut into it. You just have to apply enough pressure to force the seat wire into the center of the T and pull up. This can be quite a bit of pressure in some cases.