Every free VPS can't have OS template reinstaled in the first 24 hours of order activation. This is done for security and abuse prevention.
If you go to your free vps client area and try to reinstall OS template, you will get this message: "You will be able to reinstall your OS after 24 hours of free order activation. If you need to reinstall your VPS instantly, please upgrade to paid plan".
24 hours past your free VPS order activation you will be able reinstall your VPS operating system templates as many times as you like. If you need to reinstall your VPS instantly, please upgrade your free order to a paid plan. All paid clients have no restrictions on OS reinstallation.