If you’re no longer using an iOS device, an Apple Watch, AirPods, or a Mac, you can remove it from Find My iPhone using Find My iPhone on iCloud.com or your device. When you remove a device, it’s removed from your Find My iPhone Devices list, and if
your device has iOS 8 or later, Activation Lock is also turned off.
Before giving away or selling your iOS device, be sure to erase your content and settings (in Settings > General > Reset > Erase All Content and Settings). When you erase your content, Find My iPhone and Activation Lock are also turned off. For more information, see the Apple Support article What to do before you sell or give away your iPhone, iPad, or iPod touch. For more information about what to do before selling or giving away Apple Watch, see Sell, give away, or protect a lost Apple Watch in the Apple Watch User Guide.