How to reset my iPhone password?
How to reset my password
[Re-Titled by Moderator]
I’m guessing it’s the first link you’re seeking, but two other links to re-setting passcodes and passwords…
Forgot iPhone passcode: If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support
Set or change iPhone passcode or password: Set a passcode on iPhone - Apple Support
Set or change Apple ID password: Change your Apple ID password - Apple Support