Disallow membership plan specific welcome emails

if(!function_exists('wcfm_delete_post_meta)) {
    function wcfm_delete_post_meta($post_id, $key) {
        if ( defined( 'ICL_SITEPRESS_VERSION' ) && ! ICL_PLUGIN_INACTIVE && class_exists( 'SitePress' ) ) {
            global $sitepress;
            $current_language = $sitepress->get_current_language();
            delete_post_meta( $post_id, $key . '_' . $current_language);
        } else {
            delete_post_meta( $post_id, $key );
        }
    }
}
add_action( 'wcfm_memberships_manage_from_process', function($new_membership_id) {
    if(wcfm_get_post_meta($new_membership_id, 'subscription_welcome_email_subject', true)) {
        wcfm_delete_post_meta($new_membership_id, 'subscription_welcome_email_subject');
    }
    if(wcfm_get_post_meta($new_membership_id, 'subscription_welcome_email_content', true)) {
        wcfm_delete_post_meta($new_membership_id, 'subscription_welcome_email_content');
    }
});