<?php

namespace Bhaveshpp\Unsubscribe\Block;

class Unsubscribe extends \Magento\Framework\View\Element\Template
{
	public function getFormActionUrl()
    {
        return $this->getUrl('unsubscribe/index/index', ['_secure' => true]);
    }

    public function getHomeUrl()
    {
        return $this->getUrl('/');
    }

    public function getSedImageUrl()
    {
        return $this->getUrl('pub/media/interface/')."sad.jpg";
    }
}

<?php

namespace *\Unsubscribe\Controller\Index;

use Magento\Framework\App\ObjectManager;

/**
 * Controller to excute unsubcription request
 */
class Index extends \Magento\Newsletter\Controller\Subscriber
{

    protected $_pageFactory;
    protected $_scopeConfig;
    protected $inlineTranslation;
    protected $_transportBuilder;
    protected $_resultJson;
    protected $_captchaStringResolver;
    protected $_captchaHelper;
    protected $dataPersistor;

    public function __construct(
        \Magento\Framework\App\Action\Context $context,
        \Magento\Newsletter\Model\SubscriberFactory $subscriberFactory, 
        \Magento\Customer\Model\Session $customerSession,
        \Magento\Store\Model\StoreManagerInterface $storeManager,
        \Magento\Customer\Model\Url $customerUrl,
        \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig,
        \Magento\Framework\View\Result\PageFactory $pageFactory,
        \Magento\Framework\Translate\Inline\StateInterface $inlineTranslation,
        \Magento\Framework\Mail\Template\TransportBuilder $transportBuilder,
        \Magento\Captcha\Helper\Data $captchaHelper,
        \Magento\Captcha\Observer\CaptchaStringResolver $captchaStringResolver
    )
    {
        $this->_captchaHelper = $captchaHelper;
        $this->_captchaStringResolver = $captchaStringResolver;
        $this->_scopeConfig = $scopeConfig;
        $this->_pageFactory = $pageFactory;
        $this->inlineTranslation = $inlineTranslation;
        $this->_transportBuilder = $transportBuilder;
        parent::__construct($context,$subscriberFactory,$customerSession,$storeManager,$customerUrl);
    }

    public function execute()
    {
        if ($this->getRequest()->isGet() && $this->getRequest()->getParam('email')) {
            $email = $this->_request->getParam('email');
            $this->nowFinalyUnsubscribe($email);
        }
        elseif($this->getRequest()->isPost() && $this->getRequest()->getPost('email')) {
            $formId = 'unsubscribe_form';
            $captcha = $this->_captchaHelper->getCaptcha($formId);
            if ($captcha->isRequired()) {
                if (!$captcha->isCorrect($this->_captchaStringResolver->resolve($this->getRequest(), $formId))) 
                {        
                    $this->messageManager->addError(__('Incorrect CAPTCHA.'));
                    $this->getDataPersistor()->set($formId, $this->getRequest()->getPostValue());
                    $this->_actionFlag->set('', \Magento\Framework\App\Action\Action::FLAG_NO_DISPATCH, true);
                    $this->getResponse()->setRedirect($this->_redirect->getRedirectUrl());
                }else{
                    $email = (string)$this->getRequest()->getPost('email');
                    $this->nowFinalyUnsubscribe($email);
                }
            }

        } else {
            return $this->_pageFactory->create();
        } 
    }

    public function nowFinalyUnsubscribe($email)
    {
        $result = __('You have successfully unsubscribed %1 Email.', $email);
        try {
            $this->validateEmailFormat($email);
            $this->validateEmailAvailable($email);
            $subcriber = $this->_subscriberFactory->create()->loadByEmail($email);
            $subcriber->unsubscribe();
            $this->messageManager->addSuccess($result);
        } catch (\Magento\Framework\Exception\LocalizedException $e) {
            $this->messageManager->addException($e, __('There was a problem with the unsubscription. %1',$e->getMessage()));
        } catch (\Exception $e) {
            $this->messageManager->addException($e, __('Something went wrong with the unsubscription. %1',$e->getMessage()));
        }

        if ($this->_redirect->getRedirectUrl() === $this->_url->getBaseUrl()) {
            $this->getResponse()->setRedirect($this->_url->getBaseUrl().$this->getRequest()->getFrontName());
        }
        else {
            $this->getResponse()->setRedirect($this->_redirect->getRedirectUrl());
        }

    }

    public function validateEmailFormat($email)
    {
        if (!\Zend_Validate::is($email, \Magento\Framework\Validator\EmailAddress::class)) {
            throw new \Magento\Framework\Exception\LocalizedException(__('Please enter a valid email address. %1 is not valid Email', $email));
        }
    }

    public function validateEmailAvailable($email)
    {
        $subcriber = $this->_subscriberFactory->create()->loadByEmail($email);
        
        if ( !$subcriber->getId() ) {
            throw new \Magento\Framework\Exception\LocalizedException( __('Subcriber %1 not found.', $email)
            );
        } elseif (!$subcriber->isSubscribed()) {
            throw new \Magento\Framework\Exception\LocalizedException( __('Subcriber %1 is not active.', $email)
            );
        }
    }

    private function getDataPersistor()
    {
        if ($this->dataPersistor === null) {
            $this->dataPersistor = ObjectManager::getInstance()
                ->get(\Magento\Framework\App\Request\DataPersistor::class);
        }

        return $this->dataPersistor;
    }
}