Restore your iOS or iPadOS device in iTunes on PC
You can use iTunes to reinstall the software on your device and restore it to its default settings. You might need to do this if you’re having problems with the device (for example, if it freezes or crashes frequently) of if you’re getting ready to sell or give away your device.
Important: Restoring software on iPhone, iPad, or iPod touch deletes all your information and settings. However, iTunes backs up your device before restoring it, so you can use the backup to restore your device to how it was when you last used it.
Connect your device to your computer.
In the iTunes app
on your PC, click the Device button near the top left of the iTunes window.
Click Summary.
Click Restore, then follow the onscreen instructions.
Restoring software on your iOS or iPadOS device deletes all your information and settings, but doesn’t erase it. Deleted information can’t be accessed through the device’s controls, but it remains on your device. To find out more about erasing all content and settings, see the Apple Support article Restore your iPhone, iPad, or iPad to factory settings.
If you’ve enabled Find My iPhone, Activation Lock is on. You need to turn off Activation Lock before the new owner can activate iPhone under their own account. For information about turning off Activation Lock, see the topic in iCloud Help Activation Lock in Find My iPhone or the Apple Support article Activation Lock for iPhone, iPad, and iPod touch.