Swing it back and forth while pulling up on it
It will eventually come off.
This happens when you don't take it off to often.

Use one hand directly as possible under the hinges and lift straight up as
you use the other hand to work the door open and closed. Keep a close eye on
the fingers under the hinges as you are closing the door and lifting
straight up ...

If you have the full size doors be certain you have a good hold, those
doors weigh ALOT more than they look.  So don't drop it.  I almost
gave myself a hernia the first time as I didn't know how heavy they
really were.

I roll down the window and place my shoulder under the top of the hard
door.  I then stand, putting the weight of the door on my shoulder
while swinging the door back and forth.  It should come out.  If it's
really stuck place some penatrating oil in the hinge.

When you put the door back on, place some chassis or lithium grease in
the hinge.  That way they come off easier next time.

If you really stuck, maybe knock up with a piece of wood from
underneath?