Documentation is available for all versions going back to Python 1.4.

https://docs.python.org/release/1.4/

As it should be: I'm surely not the only person who has need to check old versions of the documentation from time to time. Not everyone is using the latest version of Python, and some times we need to write code that supports old versions. Leaving the old docs available is not merely "doesn't hurt", but is positively a GOOD thing to do.

We shouldn't remove the docs from the server, and we shouldn't break existing URLs.

I don't think there's much we can do about search engines: they have their secret algorithms for ranking pages, and whatever comes up is what comes up, and I doubt we can control that.

I expect that the only thing we could do is put a prominent note at the top of each page "This is an unsupported version of the docs, for the latest version see blah blah blah" and link to the most recent version.