The reason most oven doors are taken apart is for them to be cleaned. If you notice the ovens inner door glass is dirty the thought has probably crossed your mind how do you get inside.
The first step is to remove the door, removing the door will allow access to the lower screws. The oven door depending on manufacture will come apart several ways, the door needs to be put into broil position and lift up, also common are locking hinges, the range hinge has a lock that prevents the door from falling or being pulled off. Unlocking the hinge involves pulling the tab down into position, a small screwdriver works fine.
Placing a mat below the door will help prevent damage. Remove the screws that are located on the bottom and top of the door, some model have screws on the side. With all of the door screws removed the door will come apart, take extra caution not to bind the inner glass when separating the door, doing so may break the glass.
With the range or oven door in two pieces you will now be able to remove the brackets that hold the glass. Usually there is a thin piece of metal that holds the glass to the inner door liner, remember what brackets go where for proper reassembly.
With the brackets removed the door glass will lift out of place, clean the glass and reassemble the oven door. The insulation that lines the glass will often flake of leaving fiberglass on the oven glass, take your time when placing the door back together, this will help the insulation stay of the glass.
If you are repairing your oven door because the glass shattered or was broken, a mat below the door when taking apart will help keep the glass contained. A mat will also help the door stay in place and not slide around when pressure is applied to the disassemble screws.