They should not be... What holds the grips on are your control housings. The grips have grooves in them that fit inside your control housings, so just take apart the housings and the grips come right off. Throttle grip is a little tricky due to the throttle cables, but take your time and it is straight forward enough.
I cut the left one off with a knife. Throttle side takes longer because of the cables and thingies inside that hold the cables to the throttle. Don't lose any of those thingies.
Right is held on by controls, Left is glued on, but can be removed by injecting mineral sprits into the grip. \\; Then re-apply with two sided tape w/ mineral spirits.
 \\;
Hope this helps!