Success !! I have this type of plastic hinge on my OverheadDoor 9'x7' doors (3 hinges per panel). Finally painting the inside of the garage after 14 years, decide to remove the doors to replace some weathered sheetrock. So separating the panels seems the best method.
I used a small flat bar and a putty knife, here's my process . . .
1) Start with the left or right hinge, then move to the center hinge and then the remaining hinge.
2) Wedge the putty knife into the back portion of the plastic hinge clip, between the door pin and the plastic edge and then make sure the putty knife is centered (see image).
3) Once the putty knife is inserted in the back section of the hinge (it should stay-put on its own). I then use the hook end of the flat bar against the putty knife and the outside edge of the plastic hinge clip, lifting the flat bar will push the putty knife backwards and also pry open the closer edge of the plastic hinge, you can hold this situation with one hand, then use a flat-blade screw driver to carefully pry up the door pin it should pop out.
Hope this helps a few folks out there.
-michael