Impact of Removing 60,000 Page from Sites

[MJTrevens]

We currently have a database of content across about 100 sites. All of this content is exactly the same on all of them, and it is also found all over the internet in other places. So it's not unique at all and it brings in almost no organic traffic.

I want to remove this bloat from our sites. Problem is that this database accounts for almost 60,000 pages on each site and it is all currently indexed. I'm a little bit worried that flat out dumping all of this data at once is going to cause Google to wonder what in the world we are doing and we are going to see some issues from it (at least in the short run).

My thought now is to remove this content in stages so it doesn't all get dropped at once. But would deindexing all of this content first be better? That way Google would still be able to crawl it and understand that it is not relevant user content and therefore minimize impact when we do terminate it completely?

Any other ideas for minimizing SEO issues?

[EGOL]

You have 60,000 pages that are not unique at all.  The question is not... "what will happen when we delete it"... Instead, the question is... "What will these sites have left after it's gone".

If they are shells full of nothing... then your entire enterprise is not worth much.