Use your Phillips screwdriver to remove the two 4.7 mm screws securing the top left and bottom left edges of the heatsink.

Use your Phillips screwdriver to fully loosen the eight captive screws securing the center of the heatsink.

These screws aren't designed to come out. However, if one does come out, set it and its spring aside.

During reassembly, tighten these screws in an X-pattern to evenly compress the thermal paste.