The device name e.g. "John's iPhone" is collected from iOS devices (iPhone/iPad/iPod Touch). It is useful to identify your device when testing. You can see it in the individual device profiles in App Lists > App Users (see image below). You may not want to collect it in production. If so you can turn collection off by calling the following method, before initialising XtremePush in your App Delegate.
[XPush setNameCollectingEnabled: NO];
If you have turned this off then the Name field App Lists > App Users, should appear as blank for your devices.