OK, in the absence of any response here I finally achieved my goal by removing the words “Comments are closed” but leaving the surrounding quotes in the comments.php file. I’d prefer to make this change in my child theme, which I’ve created and activated activated within DreamHost with the line @import url(‘../twentyeleven/style.css’);.
Editing styles.css within wordpress now refers to my child theme as a parent (!). To make amendments within the child stles.css file should I add alterations after the @import line or before? Or do I create a new comments.php file within the child theme?