Pluggable function to only display images for parent categories

wc-subcategory-thumbnail.php

<?php
function woocommerce_subcategory_thumbnail( $category  ) {
	global $woocommerce;
  
	// Modification: don't show the image for subcategories
	if ( $category->parent ) return;

	$small_thumbnail_size  = apply_filters( 'single_product_small_thumbnail_size', 'shop_catalog' );
	$image_width    = $woocommerce->get_image_size( 'shop_catalog_image_width' );
	$image_height    = $woocommerce->get_image_size( 'shop_catalog_image_height' );

	$thumbnail_id  = get_woocommerce_term_meta( $category->term_id, 'thumbnail_id', true  );

	if ( $thumbnail_id ) {
		$image = wp_get_attachment_image_src( $thumbnail_id, $small_thumbnail_size  );
		$image = $image[0];
	} else {
		$image = woocommerce_placeholder_img_src();
	}

	if ( $image )
		echo '<img src="' . $image . '" alt="' . $category->name . '" width="' . $image_width . '" height="' . $image_height . '" />';
}