It should be as easy as grip and pull, but it won't be because of the 3M foam double-stick tape patches that hold them on.
All you can do is try. One of three things is likely to happen with any given strip of tape (listed from most desirable to least):
1. The tape peels cleanly from the paint and remains adhered to the underside of the plate.
2. The tape peels cleanly from the plate and remains adhered to the paint.
3. The tape splits through the middle leaving half on the plate and half on the paint.
#3 is the most likely if you use the fishing line method. #1 or #2 are most likely if you use the John Daly method (i.e. "Grip It & Rip It."). Ambient temperature may play a role as the tape could be less likely to rend itself if it's cold. Maybe try an ice water bath..
If residue is left behind, I'd be hesitant to try anything really harsh, but Goo-Gone might do the trick. It's relatively mild, but that's compared to using naphthalene (a.k.a. lighter fluid), which is just about guaranteed to work but which might also damage the paint significantly (though probably less so than the amount of rubbing required to remove the residue with Goo-Gone is likely to involve).
I'm sure others have much more experience with removing said residues than I. Anyone care to chime in?
