I’m slightly confused. But if you’re an admin which is what it looks like, you can’t revoke your own admin, Another admin has to do that for you. Whereas, any admin can grant/revoke their own moderator status and other users’ moderator status hence why you can see that button.
I’m guessing that the user has their email address in DISCOURSE_DEVELOPER_EMAILS in your app.yml.
If a user is made an admin that way, they will always be an admin and you can’t change it from the UX. Someone will need to edit the app.yml and destroy and restart the container (or rebuild).