I have ZERO desire to have a public, unrestricted share on the EX4 but it whines and says deleting the public share is forbidden. Why would anyone design a product where one cannot remove a default share that’s unwanted?
At this moment this is not possible, however, I believe there is an active Idea suggesting for the Public share to be deleted or at least blocked. You could search for the Idea, add your vote alongside your feedback, and promote it for awareness.
What you can apparently do, is to ssh into the drive (as root), and run;
cd /shares; rm -rf Public
Bingo! It’s gone. For some reason, it still shows up in the administration interface, but it remains gone from the shares directory, and, more importantly, does not show up as a share to anyone, and guest login fails.
DISCLAIMER: If you don’t know how to ssh into the drive, or to enable ssh, I’m not going to describe it. You can do serious damage if you don’t know what you’re doing, though this is pretty simple.