If I search Google for a term or my site name, Google returns the URL
sitename.com/sitemap.xml on the first or second page of the results.
I want the main site to return in the results and not the sitemap.
To remove the sitemap.xml file from your SERP, follow the steps outlined here: Google Webmaster Tools - Completely remove an entire page
To prevent this from being indexed again, add
An example for a