Reset password in recovery on Sierra
Reset password on is sierra recovery mode
Reset password on is sierra recovery mode
Standard methods of resetting passwords are Change or reset the password of a macOS user account - Apple Support . If these fail, then in Recovery Console, click on Utilities -> Terminal and type reset password (one contiguous single word) and try, if the standard methods fail.
You may also need to disable System Integrity Protection.
Reset password in recovery on Sierra