/ How to disconnect backup alarm? #1
If anything ever goes wrong in any way. You can be liable in a lawsuit. Even if the backup alarm was not directly involved. Disabling the backup alarm displays a wanton disregard for safety in general.
Is you BH being used on your property or off site? On your own property unless you are a farmer/employer you can get by with murder till an incident happens and insurance is involved. If used in construction you would not be allowed on my construction site. The OSHA rules require the horn at the decibels stated (would have to look that up). Noisy, yes. Modifications to alarm systems carry a big fine when discovered as that is considered a willful act and blatant disregard for safety. Plus the liability issue if the equipment is involved in an incident. Your insurance company will be harder on you than the State.