From virtually any Pivi screen click on the settings cog in the bottom corner of the touchscreen. Click ALL > connectivity > Bluetooth > <name of the phone you wish to delete and set-up for wireless CarPlay / Android Auto > scroll to the bottom and click on ‘Forget Device’.
Now go to your smartphone’s Bluetooth settings and find your vehicle in the list of paired devices. Delete/forget it.
Now, go back to Pivi’s Bluetooth settings and click on ‘Pair New Device’. Follow Pivi’s onscreen instructions but also look out for pop-up messages on your smartphone as you’ll need to accept some of these to ensure it connects.