If you know the iPhone passcode, go to Settings > General > Transfer or Reset iPhone > Erase All Content and Settings
If prompted for Apple ID password, enter it to turn off Activation Lock
If you forgot the Apple ID password, reset it at iforgot.apple.com
If you can’t access the Apple ID, use Apple’s account recovery process
If you have a Mac or PC, put the iPhone in Recovery Mode
Connect the iPhone to a computer with Finder on Mac or iTunes on Windows
Select Restore when prompted
If Activation Lock appears after restore, sign in with the Apple ID previously used on the iPhone
If you bought the iPhone secondhand, ask the previous owner to remove it from their Apple account at iCloud.com/find
If the device is managed by an organization, contact the organization’s IT administrator
If you cannot provide the Apple ID credentials, contact Apple Support with proof of purchase