Enter the password into the sensor alarm's control panel. Select the "Settings" menu to place the control panel in "Standby" mode. Open the control panel's lid; in some cases, you must first remove screws using a Phillips screwdriver. Disconnect the battery leads to the backup battery inside the control panel's case. Trip the circuit breaker that supplies power to the control panel or, if the control panel works off of a power cord, unplug the cord from the outlet to disable the control panel.
Use a Phillips screwdriver to loosen the screws on the sensor-receiving plate mounted next to the door frame or beneath the windowsill. Unwind the wires from around the screws. Remove the wires to disable the sensor attached to the door or window.
Use a Phillips screwdriver to remove the screws holding the wireless-sensor transmitter to the side of the door or beneath the windowsill. Open the battery-compartment lid on the back of the transmitter; in some cases, you must first remove screws using a Phillips jeweler's screwdriver. Disconnect and remove the battery or batteries from inside the compartment to disable the transmitter and the sensor connected to it.
Reattach the contact leads to the backup battery. Close the lid and reattach the screws, if there are any. Return power to the control panel from the circuit-breaker box. Enter the password into the control panel to reactive the alarm.