Open the archway door to a 90-degree angle, which makes the door perpendicular to the archway.
Place shims under the door to prop it up.
Ask someone to hold the door. Use a flat-head screwdriver and hammer to tap the pins out of the door's hinges, or pull out the pins with pliers, whichever method is less work. Remove the pins completely.
Pull the door away from the hinges. Store the door for reuse, or dispose of the door.
Remove the hinges fastened to the archway using a screw gun. Place the hinges with the door if you plan to reuse the door.
Cover the holes in the archway left from the hinges with joint compound, using a putty knife to spread and smooth the joint compound. Allow the joint compound to dry overnight.
Sand the joint compound smooth to make it flush with the archway using fine-grit sandpaper. Remove the resulting dust with a cloth or tack cloth. Paint the joint compound with a matching color using a paintbrush to finish the project.