Remove 0 count tags with SQL.

 

SQL that can be used to delete WordPress terms by count:

DELETE FROM wp_terms WHERE term_id IN (SELECT term_id FROM wp_term_taxonomy WHERE count = 0 ) AND slug != 'uncategorized'; DELETE FROM wp_term_relationships WHERE term_taxonomy_id not IN (SELECT term_taxonomy_id FROM wp_term_taxonomy);

Don't forget to backup before making changes.