If all of your APs are showing a green check mark next to the host name on the Monitor page, then you'll just want to click on that green check mark, which will open the audit view. You'll want to go to the Complete tab in the audit view, and check the output shown there to see what Radius object it has in use. We'll only need this from one AP per network policy you have deployed, again as long as all APs are fully updated currently. If they are not fully updated, we'll want to push a complete configuration, and then try to delete the Radius object again. If you're unable to push a complete configuration, we'd have to SSH in to each AP and run the commands "console page 0" and "show run", and then check that output for the Radius server in use.
