This video demonstrates how to backup and perform an iPhone hard reset (aka factory reset). After the procedure is done, your iPhone will be like it was when you first unboxed it. An iPhone hard reset is handy when you want to remove all your data and settings before selling your iPhone.
Before beginning, back up your iPhone so that you can restore your data and settings into another phone, if needed. The iOS on the new phone must be the same version or newer, however.
Enable WiFi
Go to “Settings -> iCloud and tap “Back Up Now”
Once the backup is finished, tap “Find My iPhone” to disable it
Go to “Settings” -> “General”
Scroll to bottom and tap “Reset”
Tap “Erase All Content and Settings”
Tap “Erase iPhone”
The reset process can take several minutes but when it’s complete, the “Hello” screen should appear, in different languages
You can now shutdown your iPhone