If you are using a Windows VPS and if you do not have a hosting control panel on it then you can manage the DNS records manually by following the steps given in this article.
If you are using the DNS service of your Domain Registrar:
In this case, you will have to login to your domain registration control panel and make required changes in the DNS records. The steps may vary for control panel-to-control panel. In case if you need any assistance you can contact your domain registrar.
If you are using the DNS service of any third party:
In this case, you will have to login to the control panel of your DNS provider and manage the DNS records. If you need any assistance then you can contact your DNS provider.