how to by pass phone when saying Iphone unavailable

(< iOS 15.2) See this Apple article: If you forgot your iPhone passcode

If you forgot your iPhone passcode - Apple Support

(iOS 15.2 and newer) 

How to remove your iPhone, iPad, or iPod touch passcode without a computer

How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support

Following this process is the only way out if your iPhone is disabled or unavailable. The steps given in this link will help you reset the passcode -> If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...