Removing attributes from dropdown when creating Item Groups

Removing attributes from dropdown when creating Item Groups

I spent the last week or so experimenting and testing in Zoho Inventory to figure out how the system worked, and to write up some documentation for our staff with examples to guide them - overall, very happy with the software.

I finished going and cleaning out all my bills, sales, purchase orders, etc. to start with a fresh plate after testing; however, I noticed that in the Item Groups attributes dropdown, there are still all the options that I created when testing - I would like to remove these and start over.
I was able to find one other forum post about this same issue from 2 years ago, but it "wasn't possible" despite the fact that attributes can be added by accident or just by typing into the text field without realizing there was a dropdown (which is what I initially was doing). It seems non-sensical that I can control nearly everything, including options in the dropdowns like "customer", but not attributes? 
This may become an issue as inventory types come-and-go, as we'll end up with a permanently expanding list of options.

Is there a settings pane or some button I'm missing to complete such an action? Thanks!