All I had to do was unscrew the bar ends, and got the grip off by wiggling a screw driver between the bar & grip. I was also replacing the handle bars so I wasn't worried about scratches. I did find that some "Goof-Off" residue remover helped the process.
Take off the bar-end weights and place the tapered end of your air nozzle (if you have a compressor) between the grip and bar. Hit the button and pull the grip off at the same time. If there's glue on the grip, the air should still take it loose, you may just have to hit it more than once.