Start with the bottom. Push the seat bottom back then up and as you hold it up pull foward. You my have to try this a few times being you first time. Then you need to remove the two bolts at the bottom of the seat back the pull up on the seat back.
You then can see how everything hooks up to reinstall.
No it is a picture of my 1989 Caprice. The brackets in 1969 where unpainted and the slot was longer but the seat is latched in place the same way.
Until you discover you are deforming the seat frame by pushing on it (bending the front and back together to make the seat frame narrower) so that you can get the latching rod to line up with the slot that lets the seat come out it is counterintuitive on how to get the lower rear seats out.
That is an ID tag from the vendor that made the seat for GM. A larger computer printed sheet is occasionally found in the seat springs. That would be the build sheet listing all of the options installed on your car as it went down the assembly line.