I had a lot of client websites and recently I had to do SEO for about 3-4 websites simultaneously.  It was all simple on page SEO, but I have a question is about XML map submission. I realize that creating the XML sitemap and adding it to the root directory is critical.  After that, you submit the XML sitemap to Google. For each website sitemap, do I need a NEW webmaster account?  Or can I have a universal account from which I can submit the sitemap for each of my client websites? 
Can sitemaps for multiple sites be added to Google Webmaster Tools through a single universal account?
google search console;xml sitemap
Sitemaps can be submitted for multiple sites to Google Webmaster Tools through a single Webmaster Tools account.  You can do so by adding multiple websites to a single account.   You would then need to complete the verification process for each website, or have somebody that is already verified add you as an authorized user.There are also two other ways to submit sitemaps without using webmaster tools:Name the sitemap sitemap.xml or sitemap.xml.gz in the root directory.   Googlebot checks these URLs and will automatically find sitemaps in that location.Put the sitemap into robots.txt with a line that looks like this:sitemap: http://www.example.com/examplesitemap.xmlThe advantage of submitting the sitemaps through webmaster tools is that you get statistics about the URLs in the sitemaps and see any errors.