Remove links from images in Wordpress functions.php

functions.php

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;
}