Do you mean you only want to allow super users to post comments in a post within EasyDiscuss? You can configure this under the ACL of EasyDiscuss under the "Comments" tab.

I did as you say but in the front end there is still the message of the answers, as I remove it?

Hi there,

Those message will always shown as those prompted steps are to make sure that other than super users, they will not be able to comments on the site.

Once they are logged in to the site, it will determined which users can comment to the discussion. If you wanted to remove those messages, you will required to do some customization on this file .../components/com_easydiscuss/themes/wireframe/post/default.php

Please advice.