About a year ago, I opened up a Joomla website and bought a template that had a sample content database with it. I don't know how, but Google bot came and indexed hundreds of these sample posts and pages, though the domain was new and no links pointing to it. Now I am having problems removing all the not found pages in webmasters tools. The problem is, when I try to remove the pages from webmasters tools, they keep reappearing after a week or so. These pages are non existent, so I don't understand why they keep reappearing as not found even after I remove them from index. They do not exist anywhere on the site. This has been going on for months and my rankings are dropping due to this. If I setup 404 redirect to home page, will this solve my problem? Any suggestions are more than welcome. Thanks a lot guys.
Can you share the URL of your website and few those 404 pages. If not then PM me. I may give you some suggestion. Anyway, depending upon the structure of URL, you can remove the whole directory ( URLs) using webmaster tool and can block Google by robots.txt file.
Its better to use Robots.txt file in this situation, otherwise its will keep coming up and up again even if you request Google (through Webmaster Tools) to remove these pages.
I believe if they are 404 and non existent then you probably should be 301 redirecting them. Could it be that these pages are being linked to from somewhere or linking out to somewhere?