Sometimes a comment on a forum post really is a separate question and not related to the original question. Then you can break out comments and create your own post from it.

1. Click on the menu for the comment.
2. Select Own post.
   
   
3. Select category and write a new heading for your new post. (Needs to be done also if you are going to archive the post.)
   
   
   
4. Click Create new topic.
5. Klick on click here to see the new post to see the new post. 
6. Now you can manage the comment as a completely separate post where you can e.g. archive, edit, assign, tag and of course reply!