1. Open the Control Panel by clicking on the Control Panel tile on the Start Screen.
2. A control panel Window opens. Scroll down and click on the More Settings.
3. Click on the Hardware and Sound.
4. Next, Click on the Pen and Touch. Depending upon the hardware availability in your system the option might differs. In some system you might notice other option like Biometric Devices, Fingerprint reader etc.
5. Next, In the Pen and Touch box, click on the Touch tab. Then disable ‘Use your finger as an input device’ by unchecking on it. Finally click or tap Apply button. Later, if you want to enable it then check ‘Use your finger as an input device’. That are the complete steps to disable touch screen on Windows 8