how can i get the outside light to go on and off as if the alarm is set but?

i have had to stop the alarm , which went off on it's own, by just putting in 0123 and press reset ( i have a accenta G3) which is now 5yrs old.
i don't use the alarm system, as i don't use the front door where it is set at.
but i would like the external light to go on and off like it did before.