after updating the content, page URL gets changed and a version number is getting added. For example www.sitename.com/site/home-2 when I edit home page content. How to stop SilverStripe not to use version number
If it appends a number like that that means the theres a home page already (you cant have 2 pages with the same URL for obvious reasons :D). Is there any sign of a page with the url 'home' in your cms?
Sometimes it may also be a database thing so if you have phpmyadmin login to that and view the 'SiteTree' , 'SiteTree_Live' and 'SiteTree_Versions' I think are the 3 that store page info. Do a search on those 3 and see if any of them have a record of a page with 'home' as the URL.