If you need to reinstall your VPS or change your Operation System, you can do it directly from its integrated control panel.
1 - Access your Impreza control panel
2 - Go to your VPS service and click Manage.
3 - Inside your service page, go down to the block called "Reinstall Your Instance".
4 - Choose the OS and click in Rebuild ( Remember to backup all your data before reinstallation in a different place, or all your data will be lost)
5 - Wait 20 minutes and your server will be back online with the new operating system installed.
6 - After that, restore your data backup.