Locked Out, Forgot Lock or Restrictions Passcode, or Need to Restore Your Device: Several Alternative Solutions
Forgotten Restrictions Passcode Help
You will need to restore your device as New to remove a Restrictions passcode. Go through the normal process to restore your device, but when you see the options to restore as New or from a backup, be sure to choose New.
You can restore from a backup if you have one from BEFORE you set the restrictions passcode.
Also, see iTunes- Restoring iOS software.