You can use iTunes to reset iPhone without restriction passcode.
First, turn off the ‘Find My iPhone’ feature then backup your iPhone.
Connect iPhone to the computer and launch iTunes. Your iTunes need to be updated to the latest version.
Then click the ‘Summary’ tab > ‘Restore iPhone’.
Click once more on ‘Restore’ to confirm the restore action.
Then go to the ‘Update Window’ and click ‘Next’ > ‘Agree’.
You just reset your iPhone without the restriction passcode.