You will have to give more details like make and model of the alarm as there are many different types and isolation sequences. its why no one has answered most likely.
Bob
January 2009
omiting one of the zones would have to be programmed in the engineers mode.
try www.ukpanels.com/forum1
for more info
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix home alarm systems.