[BrianG]

Even though thermal epoxy is considered permanent, you can remove it, but it's quite a bit of work. First, freeze the chassis/ESC in a freezer for about 1/2 hour. Then, gently use a screwdriver to pry up. It should pop loose with a little force. Now this is where the work comes in; use a flat exacto blade to scrape off the epoxy. I would use a fresh one to avoid scratching the surface too much.

I know this works because I've done it twice. It works good on something rigid like the case, but I definitely would NOT try it on anything directly attached to the FETs. Chances are the solder joints on the FET pins (or the pins themselves) would break before the bond would.