Right, I know where the siren is located so I took the front wing off to disconnect the siren (it goes off sporadically).

I assumed there would be a plug I could disconnect but there isn't. All the cables go into the top of the siren and out into the front of the car. Can I just cut the cable or will this cause me more issues?

A sleeve of cables go into the front dash of the car, there is one single thin cable which goes into the engine bay. Is there a plug in the dash which I can reach if I take the side panel off maybe?