ini_set('memory_limit', '2056M');
ini_set('max_execution_time', 900);

$params = array(
    'posts_per_page' => 1000,
    'post_type' => 'attachment'
);
$q = new WP_Query( $params );
if( $q->have_posts() ) :
    while( $q->have_posts() ) : $q->the_post();
        wp_delete_post( $q->post->ID, true );
    endwhile;
endif;
wp_reset_postdata();