Yep, they are bolted on and sealed, the two bolts are visible in the picture. I am not sure if the sealant is used to locate the hinges for alignement purposes, or to simply keep water out.

To put the door back on it will be easier to take the fender off, so you have easy access to the hinge bolts. You have to remove the marker light, and several bolts to do it, and don't forget the ones at the bottom of the cab.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed