How to change or reset your iPad's passcode, even if you don't remember what the passcode is

To reset or change your iPad's passcode, you can use the "Passcode" menu in your Settings app, or reset the entire device.
来自MSN

Regain Access to Your iPad: What to Do If You've Forgotten Your Password

Unlock, Reset, and Secure Your iPad: Solutions for Forgotten Passwords and Passcodes You can reset your Apple ID password using Apple's website if you forget it. If ...