method 1:
SELECT *
FROM wp_posts a
LEFT JOIN wp_term_relationships b ON ( a.ID = b.object_id )
LEFT JOIN wp_postmeta c ON ( a.ID = c.post_id )
LEFT JOIN wp_term_taxonomy d ON ( d.term_taxonomy_id = b.term_taxonomy_id )
LEFT JOIN wp_terms e ON ( e.term_id = d.term_id )
WHERE e.term_id =<category id>delete a,b,c,d
FROM wp_posts a
LEFT JOIN wp_term_relationships b ON ( a.ID = b.object_id )
LEFT JOIN wp_postmeta c ON ( a.ID = c.post_id )
LEFT JOIN wp_term_taxonomy d ON ( d.term_taxonomy_id = b.term_taxonomy_id )
LEFT JOIN wp_terms e ON ( e.term_id = d.term_id )
WHERE e.term_id =<category id>delete FROM wp.wp_terms;
delete FROM wp.wp_term_taxonomy;
delete FROM wp.wp_term_relationships;
delete FROM wp.wp_posts;
delete FROM wp.wp_postmeta ;DELETE FROM `wp_posts`
WHERE `post_type` = 'prefix-numberplates'
LIMIT 0 , 10000
