Msg#: 4517277 posted 8:30 am on Nov 8, 2012 (gmt 0)
Delete them, don't redirect them ... If the pages are really not quality and they are not going to be improved, then take them down and if you will not be putting information back on the same URL, personally, I would use a 410 rather than a 404.
Redirecting a large number of pages to one can be much worse than just removing the pages, because a 301 redirect should be to an 'essentially the same page' or 'another source' for similar/same content and there's no way you'll replace any significant portion of the content on 10,000 pages with one page, so it's really not a good use of a 301 redirect.
If you're worried about visitors, I would suggest putting up a nice custom 404 page with links to your key resources and letting them navigate to the information they're interested in.
Msg#: 4517277 posted 9:55 am on Nov 8, 2012 (gmt 0)
404 says the page is not found. If that is right then it is not an error and there is nothing to correct.
However, for pages that have gone away, you should use 410 instead of 404. It's a better signal.
For redirects, the old URL should redirect to a page that is close in topic/content to the old one. It is not appropriate to mass redirect large numbers of old URLs to a single new URL and especially not to the root index page.