@valuxai I assume you are trying to replace your thermal paste. You will need to remove the cooling fans as well as the heatsink. It does come out as an assembly. Since iFixit does not yet have a specific guide for that, use something like [https://www.youtube.com/watch?v=4fXLGr3TxcA|this video] to work on it.
Now for the repasting use something like this guide [guide|744] It'll show you how to apply the thermal paste.
While you work on your laptop, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.
Repair is War on Entropy!