If ya wanna save it, remove the bars from the bike, get some Ru-glyde, put enough in a coffee can to submerge the grip, let it soak 5-10 min. Dry the grip with a cloth so you can grasp it and wiggle it like you would the throttle side, (vroom-vroom noise optional) the Ru-glyde should creep its way between the rubber inserts/tube breaking the bond allowing the rubber tube to stay on the bar, then it can be twisted with pliers/channel locks to break the grip glue loose.
Or just cut the SOB off. Done.
Good luck!
And yes, i'm gonna have to cut the one off the throttle side, eventually, I won't harm the aluminum 1-B throttle tube!