You can do this in two ways:
A: Simply replace the red "Audible Alarm Trigger", back into the bottom of the KATANA Safety Wallet. (See #3 in the diagram below)
B: Simply click "I'm ok" in the KATANA Safety App.
Important: At some point, you must reinsert the red "Audible Alarm Trigger" so that the Arc is ready for another audible alarm should you need it.