Depends on the type of pole, aluminum or composite.
Aluminum- simply stand at an open door, raise the grip well above the top of the door, with the pole lightly touching the door itself. Sharply pull down on the shaft, and voila', the grip is off. As DH has suggested, remove the screw holding the strap on. This is only applicable witht the WC poles.
As far as cutting it, I would strongly suggest using the tubing cutter (ace hardware, $2-3) It will save you must grief about getting the grip back on easily.
Composite- some grips can be removed as above, but some need to be heated. A heat gun (gently) or hot water will do.
Cutting- wrap duct tape around it at the cutting point. Gently, in a revolving stroke, use a hack saw to score the cut through the tape. Once the initial scoring is complete, continue revolving the shaft as the cut deepens. Do not try to cut all the way through in one spot before turning. It will cause splintering of the composite material. By the way- that's why the tape is applied- to reduce the splintering.

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[ January 19, 2003, 03:41 PM: Message edited by: vail snopro ]