add_filter( 'the_content', 'attachment_image_link_remove_filter' );
function attachment_image_link_remove_filter( $content ) {
$content =
preg_replace(
array('{<a(.*?)(wp-att|wp-content/uploads)[^>]*><img}',
'{ wp-image-[0-9]*" /></a>}'),
array('<img','" />'),
$content
);
return $content;
}