Go to the VM Manager control panel. Or, in the main control panel, under "Virtual servers", select your server and click "To panel".
Then go to Virtual Machines and choose a server and press Reinstall button.
You can choose one of the following operating systems from the list of our templates:
- CentOS 7-amd64
- Debian 8-x86_64
- Debian 10-x86_64
- FreeBSD 10-amd64
- FreeBSD 11-amd64
- FreeBSD 12-amd64
- Ubuntu 14.04-amd64
- Ubuntu 16.04-amd64
- Ubuntu 18.04-amd64
- Ubuntu 20.04-amd64
If you purchase Windows 2012, you can reinstall it from the VM Manager control panel too.
You can install any other operating system except Windows (Windows could be purchased only at the time of ordering server and cannot be installed later) on your machine for free. To do this, you only need an operating system image in the .iso format. Read here