Check whether they're indexed.
If they're indexed, check if / where they rank. The articles that show up in top 100 are worth at least considering keeping (if they target good keywords and the content is decent). They might not be getting traffic right now, but they might get tons of traffic soon with only a few edits and / or links...
If they're not in top 100 but they're still indexed, check which keywords they target and decide whether they're worth improving / keeping, or - if you feel like the competition is too tough for those keywords, or that the content doesn't fit into your site, thematically... or that those articles don't target any keyword - check if they have any good backlinks. If they do, 301 them to the most relevant / similar article on your site or - if there's no such article - 301 them to the homepage.
I know that you've said that you want to delete them, but 50 pieces of content should not be removed just like that without at least making sure that they are completely useless in terms of topicality, content quality, rankability, and backlinks. It would be a shame to see them all gone when you could spend 10 minutes to 301 them to the right section instead...
Should you still wish to delete them, though... you will be left with many 404 pages which will hurt the rankings of your site, so be sure to either 301 those pages to the main category / silo, or to the homepage if there are no relevant categories / silos that they initially belonged to...