A butterfly screw is a screw that has two small metal "wings" on the top of the screw in lieu of a Phillips or flathead screw head. The wings allow you to screw and unscrew without a screwdriver. In some cases if lined up properly the "wings" can be used to support hanging things off of them, such as a painting. Sometimes you have to remove these screws if they need replacement or become stuck.
Grasp the tip of the butterfly screw with your fingers. Turn the screw counterclockwise to loosen the screw.
Continue turning until the screw comes out of the hole or bracket. If the screw is not moving or is stuck, proceed to step 3.
Grasp the tip of the butterfly screw on one of the wings on the screw head with a pair of pliers.
Clamp down the pliers. Turn the pliers and screw counterclockwise until the screw is removed.
Try turning clockwise a bit, then reversing to counterclockwise to free a stuck screw.
Do not try to pry out a butterfly screw with a hammer or pry tool. This can damage the threading of the screw and the screw hole.