Rather than tell Google via a 404 or some other command that this page isn’t here anymore, consider permanently redirecting a page to a relatively similar page to pool any link equity that page might have.
My general rule of thumb is to make sure the information (and keywords) are contained in the new page – stay on the safe side.
Most already know the power of a 301 redirect and how you can use it to power even totally unrelated pages to the top of Google for a time – sometimes a very long time.
Google seems to think server side redirects are OK – so I use them.
You can change the focus of a redirect but that’s a bit black hat for me and can be abused – I don’t talk about that sort of thing on this blog. But it’s worth knowing – you need to keep these redirects in place in your htaccess file.
Redirecting multiple old pages to one new page – works for me, if the information is there on the new page that ranked the old page.
NOTE – This tactic is being heavily spammed in 2016. Be careful with redirects. I think I have seen penalties transferred via 301s. I also WOULDN’T REDIRECT 301s blindly to your home page. I’d also be careful of redirecting lots of low-quality links to one URL. If you need a page to redirect old URLs to, consider your sitemap or contact page. Audit any pages backlinks BEFORE you redirect them to an important page.
I’m seeing CANONICALS work just the same as 301s in 2016 – though they seem to take a little longer to have an impact.
Hint – a good tactic at the moment is to CONSOLIDATE old, thin under-performing articles Google ignores, into bigger, better quality articles.
I usually then 301 all the pages to a single source to consolidate link equity and content equity. As long as the intention is to serve users and create something more up-to-date – Google is fine with this.