How to Rename an iPhone
When an iPhone is initially synced with iTunes, the user is prompted to name the device. Once the device is named, it will display on the left-hand side of the iTunes screen along with an icon of an iPhone. Users can rename the iPhone to whatever they like, as often as they like. Changing the name of an iPhone is very simple and takes less than a minute to complete.
Connect the iPhone to the computer via the USB cord.
Open iTunes if it does not open automatically. Once iTunes recognizes the iPhone it will automatically sync the iPhone with iTunes. Once the syncing process is done, the iPhone can be renamed. The iPhone cannot be renamed during the syncing process.
Locate the iPhone icon on the left-hand side of the iTunes screen.
Double click on the current name of the iPhone. Type the new name and click on the computer's "Enter" key to save the changes.