It took a good 10 minutes with the hair dryer warming the heat sink, before the stock goop let me gently wiggle the ROG cooling free.
Remove the 4 screws and all pins before starting.
Never pull up! Just gently wiggle side to side. It will start to move when it's ready....
Ware a glove as the sink get's hot with hair dryer heat blowing on it.
Mine was coaxed off successfully.
Try to avoid over heating the mobo if possible.
The stock goop will be semi-molten when it slides free. It is the ideal time to use some acetone to clean the rest off.