The antitheft system on your Honda Accord helps to prevent unauthorised starting of the vehicle. But, if you need to change your battery, you will need to disable the alarm. If you forget to do this it will go off and you'll need to reset the system. Once the alarm goes off, you need to know how to shut it off, and then how to reset the antitheft system. All you need for this is your ignition key.
Insert the ignition key in the Accord's driver-side door lock.
Turn the key to the unlock position.
Turn the key to the lock position.
Turn the key back to the unlock position. The alarm should now be disabled.
Start your Honda Accord's engine and allow the vehicle to run for at least 10 minutes. This will allow the Accord to reset the alarm. When you're done, you can shut off the Accord and arm the system as usual.