I floundered around with this for about an hour on Friday and of course I find the answer right away today:
Seems that there is a red x on the far right in the request offering tab for any RO that is in design.
Might be worth noting that this doesn't exactly delete the offering.
Providing access the the ServiceReqTemplate workspace allows us to see all Offerings and deleting them from the standard 'Request Offering' interface puts them into a 'Retired' status. I imagine this is useful for Service Portfolio purposes.