To remove the door on a Maytag Whirlpool style microwave you will need to start by removing the air grill.
The screws on the top side of the grill secure it to the microwaves cabinet, remove and either slide or lift up and out of place.
With the grill removed you will be able to lift the door up and out of the hinge. Some models will have a small set screw in the top side of the screw, by removing it the door will lift up and out of the bottom hinge.
To install set top stud into hinge moving the door back down into the bottom hinge, when in place replace top set screw if necessary.
Models that have the hinge that enters the top side of the unit will need to be taken off the wall to access the door screws.