89 cougar alarm

I just bought a 89 cougar.. n the prevouis owner lost the alarm remote.. n i want to disalarm the alarm permantly.. how would i do this? i tried cutting the wires to the siren.. but that just made it so the car wont start.. any diagrams that can help me find the main box or which wires to cut? thank u

Is it factory or aftermarket?

stock alarm.. all i pretty much need is a diagram.. i cnt seem to find one