public function removeSettingItem($owner, $code)
    {
        if (!$this->items) {
            throw new SystemException('Unable to remove settings item before items are loaded.');
        }

        $itemKey = $this->makeItemKey($owner, $code);
        unset($this->items[$itemKey]);

        if ($this->groupedItems) {
            foreach ($this->groupedItems as $category => $items) {
                if (isset($items[$itemKey])) {
                    unset($this->groupedItems[$category][$itemKey]);
                }
            }
        }
    }