Remove apple ID

To unlock your iPhone, follow the steps described in the Apple article:

(< iOS 15.2) -> If you forgot your iPhone passcode

If you forgot your iPhone passcode - Apple Support

If you don't have a computer and you can't borrow one, you need to go to an Apple Retail Store or Apple Authorized Service Provider for help.

(iOS 15.2 and newer) you don’t need to have a computer -> If you see an iPhone or iPad unavailable message or Security Lockout screen

If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

See also -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

If the iPhone is activation locked to an old Apple ID of yours and you're the original owner and can provide valid proof of purchase information

you can start an Activation Lock support request.