my kid for got her password on her iphone how can i reset it

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

(iOS 15.2 or iPadOS 15.2 and newer) 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

Has she forgotten your Apple ID?, Check her Apple ID via her email box, see this Apple article: If you forgot your Apple ID

If you forgot your Apple ID email address or phone number - Apple Support                  

OR see -> Having trouble signing in?

https://iforgot.apple.com/password/verify/appleid

Has she forgotten her password? -> See this Apple article: If you forgot your Apple ID password

If you forgot your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - 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

You can help her, see -> Help a friend or family member as their account recovery contact

Help a friend or family member as their account recovery contact - Apple Support (IN)