why must i wait 9 hours to reset password

If you mean the passcode for your phone each time you enter the wrong passcode it makes you wait longer to try again. This is to prevent an evil person from just trying all combinations in the hope of breaking into your phone. If it’s up to 9 hours you must have made a lot of wrong guesses.

If you mean your Apple ID password the same principle applies.

Yes, it is a security feature. Or you can do this now -> If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support