Your internal link structure does help your rankings, but the way I see this, there's not going to be any change to the pages that are actually ranking, right? If you remove the page that didn't rank for the keywords anyway, It shouldn't impact the rankings of the other pages.
There are a couple of factors to take into account when you do this:
- Don't forget to 301 the link to, for example, the level above, in this case /key/, so that direct/referral traffic to that page doesn't get 404'd.
- Is there a lot of traffic on the /cupboards-lockers/ page now? If so, how does this traffic behave, does it flow towards the other pages before converting or do they convert on this page? How is the UX (bounce rate, time on page, exit rate etc.)? These factors can help you determine what you should do with which page.
- Make sure there are no other dead ends in your page: check the sitemap and scrape your site with, for example, Screaming Frog to prevent any 404's from showing up.
- Make sure there are no products assigned to that page specifically, creating an odd URL structure on product level or a breadcrumb with missing or dead links.
Hope this helps!