How do you change throttle grip?

Depending on the type of bike but all grips are push on some are glued on the best way i have found to remove the rubber grips are to insert a blow gun in the end to open them up and then pull while twisting it off if that fails then you have to cut it off

Use a flat head screwdriver to brake the seal in the grip then cover the screwdriver in washing up liquid and force it under the grip again and move the screwdriver round the bar till the grip slides off.

Put a little WD40 on a skinny screwdriver and slide it up under the grip, then insert the little red extension tube that fit on the WD40 nozzle up alongside the screwdriver and spray a shot of WD40 under the grip. Pull the screwdriver out and work the grip around a little bit and it should slide right off. Be sure to wash off the WD40 before installing the new grip.
To install the new grip, spray a little soapy water inside the grip and on the handle and work the drip on. Let it dry over night and it should be tight.