mailjet-8.x-2.7/modules/mailjet_event/src/Controller/EventUninstallController.php

<?php

/**
 * @file
 * Contains \Drupal\mailjet_event\Controller\EventUninstallController.
 */

namespace Drupal\mailjet_event\Controller;

use Drupal\Core\Controller\ControllerBase;

class EventUninstallController extends ControllerBase
{

    public function callback()
    {
        $build = [];

        $controller = \Drupal::entityTypeManager()->getStorage('event_entity');
        $entities = $controller->loadMultiple();
        $controller->delete($entities);

        \Drupal::messenger()->addMessage(t('Event entities is removing succcefully!'));

        return $build;
    }

}