HT4113: iOS: Using passcodesLearn about iOS: Using passcodes
Currently Being ModeratedFeb 22, 2013 6:01 AM (in response to IMRawan)
If you are unable to modify certain passcode settings, there may be a configuration profile that requires these passcode options. You can find out if a profile is installed by tapping Settings > General and looking for the Profile setting between Accessibility and Reset.
For additional information, contact your network or system administrator, or refer to the Enterprise Deployment and Security guides on the Apple Business webpages.