How do you reinstall an operating system on as visio ct15

You can re-install you windows by belowing process:

Re-install Windows OS: You can format the drive and re-install a fresh window in your machine. You can install window through the CD/DVD/Pen drive or any other booting/flash device.
Reference link to process the activity of installation: https://www.lifewire.com/how-to-install-windows-7-from-usb-2626264