With the head parallel to the motherboard, insert a flathead screwdriver from the side between the heat sink pin and the x-clamp hook.

Twist the flathead screwdriver clockwise to pry the bottom edge of the x-clamp out of the groove in the heat sink pin.

If you have trouble, try using a larger flathead screwdriver.

As you twist, the x-clamp should pop off the heat sink pin. If not, try repeating the previous step before attempting this one again.