Better to skip all of the "old school" advice here and do as follows.
Park your car in the sun and let it sit for a while. This is all the the heat you'll need, epsecially in Summer. Then clean off the dirt on and around the emblems to be removed. Finally, and this is the most important part, use a good automotive adhesive remover like 3M or Sticker Shock (never Goo-Gone or Goof-Off). Squirt it liberally on the back of the emblem, where the adhesive is. (For the rear "VW," just lift up the rubber surround a bit.) Let sit a few minutes, and squirt again. Repeat 1-2 more times. Keep a rag handy to mop up any excess.
Now you should be able to slowly, carefully unpeel the emblem. The adhesive will typically stay in one piece, minimizing any junk left on the paint. Whatever's left is easily cleaned with more adhesive remover.
That's it! Simple, clean, and undamaging