UniFi VoIP - Perform Factory Reset from Recovery Mode

How to Enter Recovery Mode
When powering on your UVP take the handset off the hook and press and hold the mute button until you see the recovery mode screen. 

Navigating the Recovery Mode Menu

Upon reaching the recovery mode menu, to navigate the menu press the mute key to traverse down the menu. Once you reach the option "wipe data/factory reset" hang the handset up, then pick the handset back up. You will need to navigate down the menu again to the "yes wipe all user data" option by clicking the mute key again then hanging the handset back up.

After the phone has reset pick up the handset and put it back on the hook to select the option "reboot system now". Once the UVP reboots you device should be factory reset.