Wordpress - Delete Associated Media Upon Page Deletion

I suppose you're looking for something like this...?

function delete_associated_media($id) {
    // check if page
    if ('page' !== get_post_type($id)) return;

    $media = get_children(array(
        'post_parent' => $id,
        'post_type' => 'attachment'
    ));
    if (empty($media)) return;

    foreach ($media as $file) {
        // pick what you want to do
        wp_delete_attachment($file->ID);
        unlink(get_attached_file($file->ID));
    }
}
add_action('before_delete_post', 'delete_associated_media');

How about this? It adapts an example on the get_posts() function reference page.

function delete_post_media( $post_id ) {

    $attachments = get_posts( array(
        'post_type'      => 'attachment',
        'posts_per_page' => -1,
        'post_status'    => 'any',
        'post_parent'    => $post_id
    ) );

    foreach ( $attachments as $attachment ) {
        if ( false === wp_delete_attachment( $attachment->ID ) ) {
            // Log failure to delete attachment.
        }
    }
}

add_action( 'before_delete_post', 'delete_post_media' );