After placing flags on users, program registrations, and team registrations, you are able to see a running report of all flag types and their usage.
From the dashboard; At the top of your page, click "Settings" and then select "Flags" from the drop-down menu.
This page will list all of your flags under their respective groups; User Flags, Program Registration Flags, and Team Registration Flags. From here you can click the number next to the flag under "Attachments" and see the list of those with this flag attached to them. You can also click "Remove All" to remove this flag from all that it is attached to. After you have removed everybody attached to a flag, you will be able to click "Delete Flag" and delete that flag.