On many sites, the sheer number of pages are the biggest reason to consider improving or scaling back old content. From a technical perspective, depending on the scale of the old content you’re dealing with, pruning back the number of pages that you put forward can help increase your crawl efficiency.

In general, there are two ways to combine several old content pieces into one:

1.) 301 redirects enable website owners to direct one of the pages to the other. This means that the second page will no longer exist.

2.) The rel=canonical tag can be used in order to point from a secondary page (which will still be existing) to the preferred one to encourage Google to list only the preferred one the pages in search results.

In an in-depth tutorial on moz.com, you can learn more about strategies for dealing with great amounts of aged content.

In short, their advice is:

Optimizing and curating your existing content can give your collection of content a clearer topical focus.

Assess the value of your old blog posts:

  1. Is the old content beneficial for users?
  2. Are the old blog posts beneficial for you?
  3. Is the quality of the old content good?
  4. Are the old posts relevant?
  5. Is the aged content causing any issues?

What to do with the old blog posts you keep

  1. Improve
  2. Expand or update
  3. Promote

Source / Read more at: What to Do with Your Old Blog Posts – Moz