Ms,
I forgot! I probably took them out over a year ago. I was trying to decide how to make a board to cover the space contoured to the headliner curve on each end.
My best recollection is that I wiggled and pulled on them... and they came out! On the top of the headliner there's a tray that we all put lots of stuff in. That black plastic tray has a styrofoam strip on each side which I removed first, then I took the fillers out. I don't think the top strips had to be removed first.
I do recall taking out the grey push-in "Christmas tree" fasteners that hold the back edge of the headliner in place. That allowed the headliner to flex so the styrofoam then came out. There may have been one push-in fastener that held the block from pulling out, at the top of the block. It may have been pushed into the rectangular hole that you can see in the metal cross-piece.
I figured I'd bandsaw the styrofoam flat and put the blocks back in after I had a trim board in place.... not there yet! With the blocks removed, it is easier to trace the profile of the curves, but you do have to be careful because the grey headliner tends to show some minor fold marks instead of flexing as you pull the blocks out.Hope that helps a bit....
Ed