ringmaster

This plugin performs the simple task of replacing individual author names in feeds with the site name.
This is useful for blogs that are written by multiple authors that have the “authoritative voice” of the blog itself, 
rather than attributing each post to its individual author. This plugin makes the posts in the feeds (all feeds: rss, 
rss2, atom, rdf, etc) appear to be written anonymously, instead using the name of the site as the publishing author, 
rather than the name of the author. This prevents admins from having to edit core files to make posts in the feed anonymous.

Feed Anonymizer

Replaces individual author names in feeds with the site name.

wokamoto

This plugin modifies RSS feeds and ATOM feeds as you want.
<h4>How to use</h4>
Putting the following templates into the current theme folder, then you can use the customized feed templates instead of the default ones.
<ul>
<li>feed-atom.php – Atom Feed Template for displaying Atom Posts feed.</li>
<li>feed-atom-comments.php – Atom Feed Template for displaying Atom Comments feed.</li>
<li>feed-rdf.php – RSS 1 RDF Feed Template for displaying RSS 1 Posts feed.</li>
<li>feed-rss.php – RSS 0.92 Feed Template for displaying RSS 0.92 Posts feed.</li>
<li>feed-rss2.php – RSS2 Feed Template for displaying RSS2 Posts feed.</li>
<li>feed-rss2-comments.php – RSS2 Feed Template for displaying RSS2 Comments feed.</li>
</ul>
Note: 
When these feed templates are not in the current theme folder, WordPress’s default feed templates will be used.

Feed Template Customize

This plugin modifies RSS feeds and ATOM feeds as you want.

Feed Anonymizer vs Feed Template Customize