Small Query On HTML

I am doing few work with web site which is having around 40,000 dynamic pages. I recently found few errors in sitemap. Can anyone provide me few suggestion as how to remove this errors from sitemap.

Please provide some assistance regarding this

Update your Sitemap and upload it to your site in the highest level directory you want search engines to crawl, generally the root. If you list URLs in your Sitemap that are at a higher level than your Sitemap location, Google will be unable to include those URLs as part of the Sitemap submission.
Sign into Google Webmaster Tools with your Google Account.
Click the URL for the site you want.
Click Sitemaps.
Select the Sitemap you want to resubmit, and click Resubmit Selected.

Did you submit the sitemap to Google Webmaster Tools from
the correct site URL added to the dashboard (with-www) ?

It could be a Google error. Google frequently screws up. I've occasionally seen pages that have been gone for over a year that Webmaster Tools reports as 404 errors, even though there aren't any links anywhere to the obsolete URLs. The obsolete URLs are generating a proper 404 status code, which means that G should have removed them from their index shortly after the pages were removed.