how we can we reset without the code?

As with most alarms, ignore the key pad and locate the main contol box. Disconnect this main control box from the mains power and then open it up to reveal the large batteries inside. Pull the connectors off the battery terminals and this will deactivate the system permanently. During this process, the tamper alarm will probably sound and should eventually silence once the additional backup batteries in the outside alarm sounder run out of power. To speed up the process and kill the alarm sounder sooner, put some ear plugs in, grab a ladder and open up the outside sounder and disconnect any batteries you find in there.

Rupert
February 2020