Hello @rhosseinirad!
Sorry, but this is not possible at the moment. You can subscribe to feature request on this topic at the github to stay tuned.
But now you can unattach all attachments from comments with the next SQL-request
Please backup your database before it!
DELETE FROM wp_commentmeta WHERE meta_key = 'attachment_id';
You can execute it in phpMyAdmin in your hosting panel. If your table prefix is different from “wp_”, you will need to replace it with your own.
P.S. About your case, you need only unattach all attachments from comments or also delete them from Media Library?