public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $subscriber = $observer->getEvent()->getSubscriber();
        $email = $subscriber->getEmail();
        $websiteId = $this->storeManager->getStore($subscriber->getStoreId())
            ->getWebsiteId();
        $apiEnabled = $this->helper->isEnabled($websiteId);

        /*
         * Remove contact.
         */
        if ($apiEnabled) {
            try {
                //register in queue with importer
                $this->importerFactory->create()->registerQueue(
                    \Dotdigitalgroup\Email\Model\Importer::IMPORT_TYPE_CONTACT,
                    $email,
                    \Dotdigitalgroup\Email\Model\Importer::MODE_CONTACT_DELETE,
                    $websiteId
                );
                $contactModel = $this->contactFactory->create()
                    ->loadByCustomerEmail($email, $websiteId);
                if ($contactModel->getId()) {
                    //remove contact
                    $this->contactResource->delete($contactModel);
                }
            } catch (\Exception $e) {
                $this->helper->debug((string)$e, []);
            }
        }

        return $this;
    }