strange permalinks issue in multisite

I have a site where we created a sub-directory site called "Zinnia":
http://www.monsterecords.com/zinnia/

Later, my client decided to archive that site and just make it a page. So I created a page but noticed immediately that I couldn't of course name the slug "Zinnia" since that was taken up. I archived the site. Couldn't get the 'zinnia' slug back. Then I changed the name of the archived sub-site to something else. STILL couldn't get the Zinnia slug back. Tried a permalinks reset; didn't help.

Is there some place in the database that I'd be able to wipe out that original slug? Would much prefer to not have to use "zinnia-2" as the slug, but can't find anywhere that I can fix this from within the dashboard.

Thanks in advance...