You do not give any information about your car. If it is an older model for example and an aftermarket alarm is fitted, you could always cut and tape off the wires to the siren (usually located in the engine bay). This will permanently disable it. If you are sure you know which wire it uses, you could disconnect if from the battery terminal.
If it is a later model / you still want the alarm function then a dealer diagnostic or auto-electrician may be able to help (for a fee).
Additionally, if the alarm is factory fitted and it is sounding, starting the car usually resets it!
Hope this has helped.
Mr. Smith
November 2008
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.