With the UBQ radio on, go to the Vehicle soft key at bottom of the screen.
Then on the left there are arrow up and down soft keys, press to go down on the tiled softkeys. Go to the bottom and press the Reset soft key. At the top you will see Restart Radio, then Reset App Drawer to Default Order then Restore Settings to Default, Clear Personal Data etc. Press the Restart Radio and the unit will turn off and then reboot back to the splash screen.
Please see this video for reference.