1) Separate the plug from the smoke alarm unit.
2) Remove the battery
3) Throw the alarm unit against a hard surface as hard as you can.
4) Dispose of the unit in a soundproof container
4) Go to your local hardware store and buy a new unit, install.
If you're stupid enough to buy a replacement Kidde unit, keep a second unit on hand for when this unit fails and starts chirping, usually within 30-60 days, and always in the middle of the night..
If it's another brand, just replacing the backup battery will probably fix the problem.
