Do you want to reset your iPhone, iPad or iPod touch to factory settings? 
Then learn now how to safely erase your Apple devices and reset them to factory settings.

In a nutshell

• Create a backup of the device
• Tap "Settings"> "General"> "[Transfer/Reset device]"> “Erase all content & settings”.
• Enter code or password for your Apple ID for confirmation

Let's go!

Reseting your Apple device

1. Tap "Settings"> "General"> "Transfer/Reset [Device]".
2. Tap on "Erase all Content & Settings".
3. Next, enter your passcode or Apple ID password.
   Tip: If you forgot your passcode or Apple ID password, you can find help directly from Apple on these pages: I forgot my passcode, or I forgot my Apple ID password.
4. Confirm that you want to erase your Apple device.
5. Wait for your device to be wiped.
   It may take a few minutes for your data to be completely erased.
6. Done. 

You can find more information directly from Apple: https://support.apple.com/en-us/HT201274.

Set up Apple device again

Next, you need to set up your Apple device again:

1. Always select the "Configure Manually" option when setting up your iPad/iPhone/iPod for the first time.
2. Then in the next step, tap "Do not transfer app & data".

Please do not select the option to have your Apple device set up via an iCloud backup or do a quick boot under any circumstances.

More info: What do I need to know when setting up my Apple device for the first time?