That should work. Taking a quick look, if I set user_clear_logo_url to blank …
UPDATE metadata_items SET user_clear_logo_url = '' WHERE user_clear_logo_url GLOB 'metadata://clearLogos*';
then as an extra I could maybe lock that field by also setting user_fields to lockedFields=x where x is the field for logos that would have me golden. That would save future metadata refreshes.
Let me figure what x is 
