We have an existing sitemap with the URL: http://example.com/sitemap/sitemap.xml It was submitted to Google Webmaster Tools a long time ago and almost all the pages were indexed, but recently we crossed the 50,000 URL size limit and Google Webmaster Tools suggested to add an extra sitemap. After a little research, I found an article on Google's official blog which says to create a sitemap index file and submit it to Google Webmaster Tools. So my question is, should we create a sitemap index file with three child sitemaps entries, or just split the existing http://example.com/sitemap/sitemap.xml into sitemap.xml with 50,000 entries and sitemap1.xml with less than 50,000 entries? If the first approach seems good, then some questions arise for the existing sitemap http://example.com/sitemap/sitemap.xml, which is with almost 50,000 entries and indexed properly. What should I do with that? Should we remove this entry from Google Webmaster Tools as well as robots.txt and add a new sitemap with http://example.com/sitemap/sitemap_index.xml? What would be the impact of this?The real concern is that we don't want to mess up the SEO and indexing of pages from the start due to this change.
What should I do when the maximum sitemap size limit is reached according to Google Webmaster Tools?
seo;google search console;robots.txt;indexing;xml sitemap
You could delete the sitemap and it would not mess up the current SEO.  The purpose of a sitemap is to tell Google about pages on your site we might not otherwise discover. They help fix indexing problems, but are not required for a site to be indexed.Google (et al) are not going to de-index pages because they are not listed in a sitemap.Realistically, a well written site should not need a sitemap at all - it should be fully crawlable without one.All your solutions would work and should not harm SEO.Personally, I would go for the multiple sitemaps option and remove the others.