The TIM dows not hold the IHS onto the die,
The IHS can be removed by Extreme temperature change like -196c to +140c and back down to -196c after it heats up to room temperature just pry on the IHS or pull it off
🙂4 razor blades in the corners can help if you run into trouble.
if you dont want to use temperature you can cut the black rubber under the 4 sides of the IHS with a slim razor, dont go too deep or you will hit the resistors next to the GPU die