Most door knobs attach to the door with long retaining screws that are visible. Interior door knobs, however, will often have the screws hidden from view for a cleaner look on the door. These screws are behind the decorative cover plate between the inner door knob and the door. You will need to remove the inner door knob to access the hidden screws. Once you access the hidden screws, removing the door knob is just like any other door knob.
Open the door so that you can access both the inner and outer doorknobs. Look on the neck of the inner doorknob for a slot or hole between the back of the doorknob and the door.
Straighten a large wire paper clip out and insert one end into the hole until you feel the spring-loaded retaining pin. Pull the outer doorknob while pressing the retaining pin with the paper clip. Pull the doorknob over the retaining pin and off the door.
Look for a slot on the inside doorknob cover plate where you can insert a small flathead screwdriver. Insert the screwdriver into the slot and pry the cover off the assembly. Some covers will have a set screw on the thin edge of the cover. Remove the screw with a Phillips-head screwdriver or Allen key, depending upon the screw head. Pull the cover away from the assembly to reveal the hidden screws.
Wrap one hand around both sides of the doorknob. Your fingers will be on the outside decorative cover and your thumb on the inside retaining plate. Remove the screws on the inside retaining plate with a Phillips-head screwdriver in your free hand. The screws thread into sleeves inside the door that are part of the outer doorknob assembly.
Pull the inner retaining plate off the door and pull the outer doorknob away from the door.