i have removed them myself before.
hairdryer will do it, but for $28 at bunnings you can get a heat gun..
just undo the bolts,
then evenly apply heat to the seal area, while GENTLY BUT FIRMLY applying force on the tail light from within the boot.. it will slowly move out,
it will be like cheese on a pizza, so be careful not to let the stringy bits touch the paint anywhere.
use the heat gun to heat up the seal after the light is out, then remove with a old screw driver os something.
clean the left overs off the car body with turps and paper towel. (lots of paper towel)
then re apply new Sikaflex to the lights and reinstall them in std location. doing nuts up tight.
all should be done.