WC 3.4.0 +
Use the following remove_action and WC will default back to opening a tab with the terms and conditions page.
add_action( 'wp', 'my_project_wc_change_hooks' );
function my_project_wc_change_hooks() {
remove_action( 'woocommerce_checkout_terms_and_conditions', 'wc_checkout_privacy_policy_text', 20 );
remove_action( 'woocommerce_checkout_terms_and_conditions', 'wc_terms_and_conditions_page_content', 30 );
}