Use the Access Control pane to remove public access from whatever you are worried about. If you go to your public folder in the data browser, then select the sharing control pane by hovering at the top of the pane so the pane icons appear and then click on the rainbow icon. You should see the access control list including yourself at the top as the owner, and public (a globe icon) at the bottom as readers - in green. Delete the globe icon line by hovering at the right side, clicking on the read minus sign, and then confirming you want to remove the public. (If you need to drag it back, there is a globe icon at the bottom you can always grab to drop into the access control list.) Sorry not better documented!

Mmmmm, sorry. So, we have an #UXFAIL here. I've relayed it on to the rest of the inrupters. Obviously, we're happy if you have more detailed experiences to share, there's a bunch of frontend stuff to fix (I'm working mostly on the server side and developer experience stuff).

Why do you populate your personal details in the “thing” you don’t understand and have no control over in the first place?

Yep, an entirely valid point and the reason I called myself an idiot - I used my real name and my email and I stupidly assumed I'd have some immediate control over public visibility, or at worst, the ability to undo what I'd entered or nix the thing entirely.

Given the sign-up asks for both details and I assumed there might be some potential for further use here for a platform created by a trusted party, I unthinkingly stumbled with the minimum.

I usually - which is to say always - don't, but here did.

Not looking for sympathy or sanctimony, just relaying my experience.