Place the end of the soldering iron on the end of the wire connected to the copper cylinder to detach the wire.

If you are unfamiliar with soldering, take a look at this article: How to Solder and Desolder Connections.

To replace the alarm switch, attach one end of new alarm switch wire to the copper cylinder.

Use a Phillips #1 screwdriver to reinstall the switch screws.

Follow steps in reverse order to assemble the clock.