easiest way to remove put on grips is use a spray nozzle on an air compressor, the air bulges the grips and makes sliding on easy. Whatever you do, don't use anything like wd40 or other lube as it won't dry and the grips will slide all over the place.
here's a good vid shows how to do it
https://www.youtube.com/watch?v=Jth5AgCOwpI
note I do it slightly different and insert the nozzle from the end of the handlbar grip. YOur goal is for the air to balloon out the grip which makes sliding on / off easy.