You need to grab hold of the bottom front of the seat, kinda push down and push towards the back of the car and then pull up all at the same time.
Well, not quite all at the same time. some come out easy and sometimes they put up quite a fight. See if you can feel under the seat about a foot from the outside, You may be able to feel the catches for the seat and feel the shape of them. there is one on each side. This can give you an idea of the way you need to push and pull.Probably easiest to undo one at a time. it's kinda hard to describe in writing. (At least for me, LOL )
Dale
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1970 Riviera
1996 LeSabre
And many Buicks in the past.
I think I am, therefore I am. I think.
(George Carlin)