Power off the device and unplug it
Remove the CPU cooler or heatsink
Wipe off excess paste with a dry lint-free cloth or paper towel
Dampen a lint-free cloth or cotton swab with 90%+ isopropyl alcohol
Gently clean the CPU and cooler surfaces until the paste is gone
Use cotton swabs for edges and hard-to-reach areas
Let both surfaces dry completely
Apply new thermal paste if reinstalling the cooler
Reattach the cooler securely
Dispose of used materials properly