Hello,
1) What errors do you get while registration account there?
2) Provide us with temporary WP Dashboard and FTP access to your site to check the issue in more detail and help you.
2.1) Using WooCommerce snippet https://docs.woocommerce.com/document/editing-product-data-tabs/#removing-tabs or below CSS code
.tabs.wc-tabs {
display: none;
}
3) The header builder does not have option to choose the custom account menu. If you want to remove some links from that menu go to WooCommerce > Settings > Advanced > clear endpoints that you don’t want to show there http://prntscr.com/t8jfrl
Regards