Hi Lee,
If you want to disable touch screen in Windows 8, then you can follow these steps.
a. Press Windows key + X and select Control Panel.
b. Go to Hardware and Sound and click on the Pen and Touch option.
c. In the Pen and Touch window, tap on Touch tab.
d. Uncheck the box for “Use your finger as an input device”.
e. Click on Apply to disable the touch display.
As your touch screen has broken, I would suggest you to contact Acer support for the query. They can assist you better with the hardware issues.
Feel free to get in touch with us for any queries related to Windows.