Use Noindex to Remove Pages from Sitelinks
If you demote Sitelinks, it just reduces their weight so they might still appear. You may have to remove the page from the index. The demotion may take ‘several’ weeks to process. If you have really bad Sitelinks which won’t disappear, but you want it to remain indexed, then you can contact them.
404 Pages Crawled Less Than Noindex
For expired/removed content, John says that Google prefer a 404 as it results in less crawling than a noindex.
Duplicate Pages with a Noindex May Be Selected
If you have duplicate pages with the same content which aren’t canonicalised, but one of the pages has a noindex, then Google might pick the noindex version, and then that page will be noindexed even if there is an indexable duplicate.
500 Error Pages May Impact Crawl Rate and Will Eventually be Treated as 404
500 errors can impact ranking. They might result in a lower crawl rate. If they are persistent, they will be treated like a 404 and dropped. Also, Google won’t see the content of a 500 page so you can’t use a meta noindex to get Google to drop those pages if that’s what you want.
Noindexing paginated pages is OK
But canonicalsing makes much more sense which he doesn’t mention.
Don’t Noindex Canonicalised Pages
You shouldn’t noindex pages which are canonicalised, otherwise they might ignore the canonical tag.
Noindex Pages Can’t Accumulate PageRank
Noindex pages can’t accumulate pagerank for the site, even though the pages can be crawled. So this isn’t an advantage over disallowing.
Unwanted Sitelinks Pages Can Be Nonidexed
Sitelinks which do not disappear after being demoted, can be removed by adding a noindex. If the Sitelinks are showing incorrect international pages, hreflang tags can be used to identify the preferred version.