how to remove wall hangers?

Insert a firm blade or a putty knife between the wall and the wall hanger. Wiggle the blade towards you slowly but firmly to loosen the screws. Repeat the process on each screw till the wall hanger is at least a few centimeters out of its place in the wall. When all the screws of the wall hanger are outside of their places at an equal distance, grasp the hanger with your fingers and pull it out of the wall.