It appears that a large number of "historic" Onos project pages remain accessible.
In fact whole wiki structures for previous versions appear to be available: https://wiki.onosproject.org/display/ONOS10/ONOS+Wiki+Home
Although these types of pages don't appear on the current Wiki, some appear high up in general search engine results. Personally these pages confused me no end until I noticed the versioning in the url.
Not sure that a wholesale culling is the correct answer since some of the pages seem to hold valuable contextual information. The best answer may be to apply a general warning banner to historic pages.