Place a ladder underneath the smoke alarm.
Climb up the ladder so that you can reach the smoke alarm and work on it comfortably.
Unlock the smoke alarm cover. If the cover has tabs, depress all tabs at the same time until you hear the smoke alarm click. If the smoke alarm has screws, unscrew them with a screwdriver and set them aside. If the smoke alarm has no tabs or screws, twist it counterclockwise until you hear it click. Remove the cover.