Removing the Heatsink
Warning: We do not recommend that the CPU or the heatsink be removed. However, if you do need to uninstall the heatsink, please follow the instructions below to uninstall the heatsink to prevent damage done to the CPU or the CPU socket.
1.Unscrew the heatsink screws from the motherboard in the sequence as shown in the illustration below.
2.Gently wriggle the heatsink to loosen it from the CPU. (Do not use excessive force when wriggling the heatsink!)
3.Once the CPU is loosened, remove the CPU from the CPU socket.
4.Remove the used thermal grease and clean the surface of the CPU and the heatsink, Reapply the proper amount of thermal grease on the surface before reinstalling the CPU and the heatsink. (Do not reuse old thermal grease.)
Loosen screws in sequence as 
shown.
Screw#4
Screw#1
Screw#2
Motherboard
Screw#3