Turn off power to the smoke detector at the circuit breaker
Remove the detector from its mounting bracket
Disconnect the wiring harness by pressing the release tab and pulling it apart
Remove the backup battery, if present
Twist off the detector from the base if it is hardwired with a twist-lock mount
Cover the exposed wiring with wire nuts or electrical tape if the detector is being removed permanently
Restore power only after the wiring is safely secured
Reinstall or replace the detector as required by local safety codes