How to remove comments/feeds URL - 404 error

An SEO tool that audits my site turns up this error:

This page links to the page "http://<my domain>/comments/feed/" (using the <link href (rel="alternate")> tag). The web server returned the error code 404 when accessing the linked page. This means that search engines cannot access the linked page, either, and that they might come to the conclusion that this page is not up-to-date.

How do I kill off the comments/feeds?