What's the intersection of "users who want to delete a specific cookie" and "users who cannot open Developer Tools"? For the average user, deleting all of a site's cookies seems like all the granularity you need (and will be a more effective troubleshooting tactic anyway).
Effectively zero. Ridiculous that anyone would think this an issue even worth discussing.
I don't think many non-developers use the dev tools for tasks, while people merely interested in technology (gamers and such) will get a gentle introduction to how cookies work from looking through the cookies in the normal interface. Those people might go on to become developers eventually.