Thermalpads I hear are a PITA. I don't have expirence with them myself.

But I found this stuff (ArctiClean) that looks like it'll work good. Review here. Never used it before since I never had Thermalpads to remove (only AS5 thermal paste, and I just wiped most of that off and reapplied - it's still all AS5 for my purposes).

I hear Isopropyl alcohol and Acetone also work, but the above review claims it doesn't work for thermal pads, and only works on thermal paste...