Modify iPhone restrictions passcode
Erasing the phone in iTunes will remove the restrictions along with everything else.

Per my comment, you can change the passcode for restrictions under Settings &gt; General &gt; Restrictions  

By clicking [enable restrictions] it will prompt you for password, you may disable it and then re-enter the passcode.

Reference as well here:
https://discussions.apple.com/thread/2478010?start=0&amp;tstart=0