Which command returns the Cisco VCS to its factory default settings?

`write erase` is a Cisco IOS command used on routers and switches to erase the startup configuration; it is not a valid command on Cisco VCS.

`factory-default` is not a recognized command on Cisco VCS; the correct form is `factory-reset`.

`xCommand SystemUnit FactoryReset Confirm: Yes` uses the xCommand API syntax applicable to Cisco CE/TC endpoint software, not the VCS appliance CLI.

`utils SystemUnit FactoryReset` uses a syntax pattern associated with Cisco Unified Communications Manager (CUCM) CLI, not Cisco VCS.

The `factory-reset` command is the correct CLI command on Cisco VCS that wipes all configuration and returns the appliance to its original factory defaults. It is executed directly at the VCS shell prompt and is distinct from API-style xCommand syntax used for endpoint or API-driven configuration.