There should be a small space in the middle of the key under the nissan logo, just put a small screw driver in there and turn 180 degrees this should separate the parts.
Looks like you will have to get a blank blade aswell. The chip needs to be the same as the old one but the covers can be a differant colour. \i have just bought a blank key and the seller has put the same chip in but a differant colour cover on the chip as he had ran out of white covers ( we shall see when I get it reprogrammed if he has supplied the correct chip) you will have to re program the fob which is very easy just google it. But getting the blade part reprogrammed in a nightmare. most people only want to supply and reprogram unless you go to the nissan dealer who charge about £80 to reprogram the blade. If you get a blake blade and the same transponder part, then get it cut DO NOT ATTEMPT TO START THE CAR BEFORE YOU GET THE BLADE REPROGRAMMED as the car will not start and you will lock the engine and will be lock out for at least 30mins.
GORDON
December 2008