Hello,
That button comes from YITH Advanced Refund System for WooCommerce plugin, it’s not theme option. So, contact the plugin author to find out if they have the option to disable it.
We can just help you to hide it using custom CSS
.woocommerce-MyAccount-content .woocommerce-order-details .ywcars_button_refund {
display: none;
}
Regards