if you have no key fob and do not know what alarm it is you would be better off removing the alarm providing it is aftermarket
if it is a factory fit one then you can leave it on the car and just add an aftermarket alarm with no problems
plus with an aftermarket alarm you can have the total closure facility to close all the windows with no extra parts required
where are you based as i am a mobile alarm fitter and i am insurance accredited too
i am in colchester essex