How to deactivate old iPhone
Here we will introduce you four ways of how to deactivate old iPhone and make your personal information keep secured.
Use iOS to reset iPhone
1. Tap on "Settings" from home screen on your iPhone and enter "General". Scroll down to the bottom of the device's screen.
2. Tap on "Reset" and there are several options displaying on the screen.
3. Select the option "Erase All Content and Settings". Then, a prompt will ask you to enter your iPhone's Apple ID along with passcode. All the data, the information, as well as the settings on your iPhone, will be removed by this operation, which includes the feature "Find My iPhone Activation Lock" on iOS 7. Restart your device after the erasing, the prompt "Slide to Set Up" will be displayed on the screen.
Use iTunes to restore iPhone
1. Tap on "Settings" on your device and enter "iCloud". If the feature "Find My iPhone" has been enabled on your iPhone, switch it off by toggling the button to the disabling position. Then enter Apple ID and passcode of your iPhone and tap on "Turn Off".
2. Run iTunes on computer and associate your iPhone with the computer via USB cable. Select your device in iTunes window.
3. Click on "Restore iPhone" from the Summary. Then choose the option "Restore" and confirm you would like to get your iPhone's factory settings reinstated. Your iPhone will restart after the erasing, the prompt "Slide to Set Up" will be displayed on the screen.
Use iCloud to wipe iPhone in a remote way
1. Get access to iCloud.com
on your computer web browser. Enter the Apple ID that you use for the service of iCloud on your iPhone. Then Tap "Find My iPhone".
2. Choose your iPhone in the drop-down menu "All Devices" in order to show the information screen of iPhone.
3. Tap "Erase iPhone" from the information screen and enter your Apple ID and passcode in the prompt. If your iPhone is running base on iOS 7 system or later, a phone number and a message must be entered to show up on the device's screen when your iPhone is erased. Wiping in a remote way will be done at once on the iPhone which is online, or the iPhone will effectively become deactivation when it pops up online. Check the email to confirm the erasure on the email address with your Apple ID.
Get rid of the SIM Card
1. Get the SIM tool with pointed end inserted into the hole beside the tray of SIM card, then eject the tray by pushing it.
2. Pull out the SIM card tray and get rid of the SIM Card.
3. Push the tray back to iPhone till a clicking noise can be heard.
For more details, check: How to Deactivate Old iPhone