Try with this, It will delete existing wp_commentmeta table then create ‘wp_commentmeta’ table :
DROP TABLE IF EXISTS `wp_commentmeta`;
CREATE TABLE `wp_commentmeta` (
`meta_id` bigint(20) UNSIGNED NOT NULL,
`comment_id` bigint(20) UNSIGNED NOT NULL DEFAULT '0',
`meta_key` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`meta_value` longtext COLLATE utf8mb4_unicode_ci
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;