We are erasing an iPhone 6s Plus running iOS 10.3, but the steps will be similar to other versions.
- Ensure that you have made backups of your iPhone files to either cloud services like iCloud or locally to your computer via iTunes. This reset procedure will make your iPhone files unrecoverable.
- Before a reset can be performed, you will need to disable Find My iPhone on this device. This measure is necessary so that only the owner is able to erase the phone.
Go to Settings > iCloud > Find My iPhone. Tap the Find My iPhone toggle to disable this service. You will be asked for the Apple ID password associated with this device. An Internet connection is required to disable Find My iPhone, either Wi-Fi or cellular data.
- Now that Find My iPhone is disabled, you are ready to perform the factory reset.
- Go to Settings > General > Reset, and tap “Erase All Content and Settings”.
- Enter your device passcode when asked and follow the prompts on the screen.
- The iPhone will shut down and reset to a factory state. When the device reboots, you will see the Hello/Welcome screen as if it is a brand new iPhone.
The entire process takes only a few minutes to complete because modern iPhones have encrypted storage. This means there is no need rewrite the entire flash storage chip, only the encryption key, and device configuration is reset.
Keep in mind that when you are selling your iPhone, you will need to be very clear whether your device is locked to a specific cell phone service provider. If you had purchased your device ‘unlocked’ directly from Apple, without any subsidy or contract, it is probably unlocked and will work with any compatible carrier. If you had purchased the iPhone from your cell phone carrier, it is likely locked to only work with that provider. Unlocked iPhones are generally more desirable and will sell for a higher price. A locked device may be unlocked by your carrier, but this service could cost money. Or you could sell the device to somebody using the same carrier. An active SIM card is also required to activate and setup an iPhone from the Welcome screen that had been factory reset.