If it is what i think it is, you want heat (hairdryer or heat gun) to soften up the glue or (more likely) double sided tape holding it on to the car. Not too much obviously, as you will damage the paint!. But that could be enough to allow you to prize it off using a flat blade screw driver. Use your finger as a lever, and put the edge of a cloth, or possible a bit of cardboard underneath the opposite egde to where you are trying to lift (otherwise that edge could dig into the paint).

If you have access to a heated power wash, that could be enough to do the job by itself, just leaving you to remove any glue or tape residue.

Failing that, (again using some heat to soften things up first) get some fishing line or strong thread, and work it back and fore behind the emblem/badge in a sawing motion.

Be aware though, that if this emblem has been on the car for a while, the paint underneath will be less faded and depending on coulour, could be very noticeable. In that case, you'd have to use something like T-Cut or some other cutting compound to bring the rest of the paint back to the same level.