I have a 99 clio grande, and put a new gearknob on it. I asked in renault, and basically (this is the way i done it) you have to take a hack saw to the gearknob, cut right down the middle untill u hit metal, then it should all come away leaving you with the metal stick to put your new knob on!
Taking a hacksaw to my beloved clio was daunting though.....