It's a bad idea to keep them if the intent to show that the information is current news. If the site is labeled as NEWS and you add that in Schema and you're presenting all old articles, Google will reclasify the site as it's not actually NEWS, it's ARTICLES. So you'd not be in any news feed system.
What I'd likely recommend would be to keep them at the moment, start the news section, generate the content and as you get new content, delete the oldest piece in the system (if it's no longer relevant).
There are some news pieces that will remain relevant long after a normal expiration date. Things like "EIG acquires XXXXXX" are great pieces as you'll always get searches of "who owns XYZ" or other hosting companies. So some will be relevant.
Others, like "layerslider version 6.0.1 is exploitable" would likely be less relevant as that version is from November 2016. That said, WordPress people have a nasty habit of not updating plugins
Windows XP has a backdoor - likely not news worthy today as pretty much nobody uses that system (almost nobody anyway).