jameskoster

add_action( 'wp_enqueue_scripts', 'jk_disable_magnification' );
function jk_disable_magnification() {
    wp_dequeue_script( 'zoom' );
}

krogsgard

<?php
/* This snippet removes the action that inserts thumbnails to products in teh loop
 * and re-adds the function customized with our wrapper in it.
 * It applies to all archives with products.
 *
 * @original plugin: WooCommerce
 * @author of snippet: Brian Krogsard
 */

remove_action( 'woocommerce_before_shop_loop_item_title', 'woocommerce_template_loop_product_thumbnail', 10);