If the door is locked, removing the knob can be tricky. Insert a thin object into the crack between the door and the frame, near the doorknob. Push the latch back or use a screwdriver to turn it. Grab the knob firmly and pull it towards you. Use a screwdriver or pliers to unscrew the screws securing the knob. Carefully pull the knob off the door. If the latch is still engaged, use a screwdriver to push it back into the door frame before removing the knob.