Enter the password into the keypad on the home security alarm system's control panel. If an LCD screen is used instead, enter the password into the virtual keypad on the screen. Go to the menu that automatically re-arms the system after a predetermined time has passed. Uncheck the setting so it is no longer active. Return to the main menu.
Enter the password into the control panel to deactivate the home security alarm system. Open the control panel's lid; screws may need to be removed or a latch unlocked first. Remove the wires from the battery backup inside the control panel. Trip the circuit breaker at the fuse box that supplies the control panel with electrical power.
Enter the password on the control panel that allows access to the menus. Navigate through the menus until you come to the "Reset" or similarly named option. Activate the "Reset" to set the alarm system to its default setting, which is the manufacturer's original setting. Leave the control panel at this menu until you are ready to re-arm the alarm system.