I used dental floss and it was very easy to remove the badge.
The left over adhesive was a different story. I tried everything I could think of, but I could not get the sticky stuff to come off. I finally tried a citrus based adhesive remover and it worked :
Lanolin from Wikipedia. a greasy yellow substance from wool-bearing animals. Then as Jimi says you just rub the adhesive around and the lanolin keeps it from sticking and eventually it comes off.
I used waxed dental floss (you are really just sawing through a thin layer of foam tape). If you keep rubbing your finger over what's left it will usually start to ball up when it comes off. Goo-gone worked for me to get rid of the residual adhesive but I imagine any lemon-degreaser type dishwashing detergent would do the same.
You can use rubbing compound to clean off any dried wax build-up from where you couldn't get under the edges of the badge in the past (it will be a "ghost" of the emblem outline).
Finish with a quick bit of paste wax and you're done. It's literally a five-minute job from start to finish.
I heated it up, pulled it off gently, and rubbed the adhesive off. I followed up with a bit of 3M glaze and my wax. Took a total of 5-10 minutes. Now I wonder if I should put the 986 emblem on......
+1 on the hair dryer trick. Then a bunch of goo gone and a lot of rubbing with your finger should do the trick.
I de-badged mine last year. Yesterday, while when I was polishing my rear deck lid, I could make out the “Boxster” script in the haze of the polish – pretty cool. I remember someone once posted a picture of water beading into the word “Boxster” on their deck-lid where the badge used to be – very cool.