You can delete a Sitemap from your account, so that it no longer appears in Webmaster Tools. However, Google may continue to fetch your Sitemap data until you remove the Sitemap file from your webserver. If you want to keep the Sitemap on your server for use by other search engines, you can use your robots.txt file to prevent Google from accessing it.
Delete a Sitemap from your Webmaster Tools account:
- On the Webmaster Tools Home page, click the site you want.
- Under Optimization, click Sitemaps.
- Select the checkbox next to the Sitemap(s) you want to delete, and then click Delete selected.