The q2a sitemap is not saved on the file system but is generated on the fly when you request it ( http://www.yourq2asite.com/sitemap.xml ).
It's dinamically generated by the xml-sitemap-plugin, that is a q2a standard plugin.
If you want to change for some reason (that I've not understood. Do you want to use 2 sitemap.xml ?) the url at which this plugin "listens" for the request, you should change the behaviour of the plugin.
See this line :
you could change it for instance
so that you can now invoke the plugin at the new url :
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.
July 15, 2020: Q2A 1.8.5 released!