Cleaning bad pages

[bele]

We have 10,000 of bad pages, which panda could track and penalize us for that.

If we delete them we will get 404 error, and after that we could again get penality from G algo.

How can i delete them to follow google rules and avoid penalities?

If we make redirect of 10k pages with 301 to index, can 10k old pages be treated as duplicate?

[BrianCrouch]

Assuming these are all on the same domain (not separate subdomains), simply permanently redirect the URLs to an existing or new upper-level category page, which most closely matches the removed content. There's no perfect solution, but that's better than all 404 errors, especially if there are good links to those old pages. Good luck.