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функция не описана

delete_post_meta_by_key() WP 2.3.0

Deletes everything from post meta matching the given meta key.

Хуков нет.

Возвращает

true/false. Whether the post meta key was deleted from the database.

Использование

delete_post_meta_by_key( $post_meta_key );
$post_meta_key(строка) (обязательный)
Key to search for when deleting.

Код delete post meta by key: wp-includes/post.php WP 5.2.2

<?php
function delete_post_meta_by_key( $post_meta_key ) {
	return delete_metadata( 'post', null, $post_meta_key, '', true );
}