To do it well (aka with as little to no damage to your paint underneath,) you'll need an old credit card or gift card, a screwdriver, and a heat gun. A hair dryer will do the trick, too.
You want to heat up the emblem with the hot air, first. This softens up the adhesive underneath it. Then you slide the plastic card underneath it, trying to pry the emblem up away from the painted surface. On my wife's Civic Si, this was all that was needed... the emblem came off with the heat and the prying card. If it doesn't come off, slide the card into the adhesive as far as you can, with the card flat against the paint. Then use the flathead screwdriver to pry the emblem away from the vehicle by wiggles the screwdriver from side to side. Make sure you keep the card firmly underneath the screwdriver, so that your screwdriver is only making contact with the emblem and the card... not the paint underneath the card. Make sure to keep the adhesive as warm as possible.... if it cools off, run the hair dryer over it for a minute or two to keep it soft.
I debadged the wife's Si like this, as well as one of my motorcycles, with zero issues. Just be patient, and make sure you don't have the screwdriver come in contact with the paint, or else you'll gouge the paint.
Ben