This is more of an instance governance question than a Builder question:
I am going through the list of Cards in Admin > Cards to do some cleanup. I see dozens of cards with the same name as a drill layer I use. It shows me as the only person with access to those cards (which would not be true of the parent card if these drills are part of viable cards in my instance). When I click on the listed card to open it in a new tab, it has a unique URL and kpi #, and says it hasn't been added to any pages.
I am wondering: can I delete these? Or will I accidentally be removing drill layers to viable cards, which I wouldn't learn until trying to drill through one of them and getting the data table instead of a drill? I can't seem to figure out how to identify the cards each of these drills attaches to, in order to test this. So have I somehow created unique KPIs that are not actually part of any of my active, viable cards in the instance?