i removed one of these spoilers today, it seemed to be just a very strong seelant glue. if you get a knife in there to start it of then i personally had to get a bit more heavy with it with a mallet and a screwdriver (flathead works well) just break the seelant alround.
The only thing is i was removing it off of a tailgate that had already been smashed off and i literally cut through the half of the tailgate to get rid of excess i didnt need. This took a bit of time and patience, and most of all care!! but if your careful you wont crack the mould too much which means any small scuffs, or cracks in the paint, or even chips can be all covered with a bit of filler or whatever you wanna use and the all ya have to do is give it a nice rub down and a fresh lick of paint.
(the above apllies to the bigger spoiler, i sorry i assumed thats the one you meant)
hope this helps.
