Can anyone tell me how to remove the seat back cushions on my 1985/C4?

Remove the entire seat from the car to make it easier to work on. If you want to remove the upper seat cushion towards the top on either side there is a small bracket attached to the seat back that catches a metal rod molded into the seat foam. Use a large flat screwdriver to push the rod out of the bracket.

Another method, firmly grab the seat back with both hands on the left or right side of the seatback bolster and pull like hell toward center of seat back.......cushion should now pop off molded seat back.......before reinstallation consume much adult beverage:food-smiley-019: