How de-index low quality pages from Google?

[richardmsmith]

If you have low quality pages in the index (this mostly covers “thin content” pages and/or pages with duplicate content) this means those specific pages, as well as your entire site, will have a reduced quality score.
Step 1 – Understand What An Indexed, “Low Quality” Page Actually Is.
Step 2 – Find These Indexed, Low Quality Pages in Google
Step 3 – Fix These “Problem Pages”