Controller/Adminhtml/FastlyCdn/Edge/Dictionary/Item/Delete.php
public function execute()
    {
        $result = $this->resultJson->create();

        try {
            $dictionaryId = $this->getRequest()->getParam('dictionary_id');
            $key = $this->getRequest()->getParam('item_key');

            if ($key == '') {
                return $result->setData(['status' => true]);
            }

            $deleteItem = $this->api->deleteDictionaryItem($dictionaryId, $key);

            if (!$deleteItem) {
                return $result->setData(['status' => false]);
            }

            return $result->setData(['status' => true]);
        } catch (\Exception $e) {
            return $result->setData([
                'status'    => false,
                'msg'       => $e->getMessage()
            ]);
        }
    }
public function execute()
    {
        $result = $this->resultJson->create();

        try {
            $dictionaryId = $this->getRequest()->getParam('dictionary_id');
            $key = $this->getRequest()->getParam('item_key');

            if ($key == '') {
                return $result->setData(['status' => true]);
            }

            $deleteItem = $this->api->deleteDictionaryItem($dictionaryId, $key);

            if (!$deleteItem) {
                return $result->setData(['status' => false]);
            }

            return $result->setData(['status' => true]);
        } catch (\Exception $e) {
            return $result->setData([
                'status'    => false,
                'msg'       => $e->getMessage()
            ]);
        }
    }
Delete dictionary item

@return $this|\Magento\Framework\App\ResponseInterface|\Magento\Framework\Controller\ResultInterface