Disable alarm siren?

My alarm went off tonight for a while. It's parked out back, at an angle on a sloping apron - I've parked it there before without any problem, though I prefer the more visible street parking out front. Anyway, I heard the alarm, from the front of the house, and didn't realise it was mine; it stopped after a while, having greatly excited the neighbour's yappy dog.
A couple of hours later, I saw a Whatsapp message from my neighbour, which read 'That's your car'. I'd forgotten about the alarm by then, so my first alarmed reaction was - what? Being towed away? On fire? What? :-o

Then remembered the earlier alarm, so went out to check. No sign of anything amiss, no damage. It's a quiet cul-de-sac, and a cut-through for foot traffic, including the local drug dealers/buyers - so maybe someone was trying to break into it. No idea.
My question is, can I permanently turn off the siren? I've found some instructions on here for temporarily disabling the motion sensor alarm, by hitting the lock button twice - IF that works for my model. But I'd rather immobilise it entirely if possible. My Roomster is 2013, automatic.
Anyone know?