enable-sidebar-for-level-3-cats.php

<?php
function wp01234556789_remove_sidebar( $is_active_sidebar ) {

	if( is_product_category() ) {

		$cat_id = get_queried_object()->term_id;
		$parents = get_term_parents_list($cat_id, 'product_cat', array( 'link' => false, 'inclusive' => false ));
		$parents = explode( '/', $parents );

		return count( $parents ) >= 3 ? true : false;
		
	}
	
}

add_filter( 'is_active_sidebar', 'wp01234556789_remove_sidebar', 10, 2 );
?>