Factory reset
Web interface method
Click on the Reset all config profiles button at the bottom of the Settings page.
If you only want to reset the active configuration profile to defaults, you can use the Reset config profile button at the bottom of the Settings page.
Console method
You can reset the active configuration profile to defaults with the cfr, and all configuration profiles with the cfa command.
You can use the Console on the Status page of the web interface, or through the USB serial console.