I submitted sitemap1.xml to google, but discover there were errors in the urls. I then deleted the sitemap1.xml, and correct the error, and resubmit as sitemap2.xml (I should not have changed the name, but it has been done).
Googlebot now retrieves urls from both sitemaps, and of course the urls in the 1st sitemap doesn't exist. How can I stop it?
the bad news is: you can't change it. Only time will (that sounds like a song, doesn't it? ;-) The good news is: you don't need to worry about it. It just produces one 404 error a day, which costs you nearly no traffic.