# First:

DELETE FROM wp_postmeta
WHERE post_id IN
(
SELECT id
FROM wp_posts
WHERE post_type = 'attachment'
)
;

# Second:

DELETE FROM wp_posts WHERE post_type = 'attachment'

http://wordpress.org/support/topic/delete-100000-images-from-media-library

Run these queries (phpMyAdmin will do) to delete all media in the library, and remove all post attachment affiliation

SQL query to delete all media and attachments in wordpress

sql, wordpress

SQL