You can’t turn off the Touchpad on a Windows 10 Asus laptop by using Fn + F9 keys combinations. In order to disable your Asus touchpad, just follow the simple steps below. Keep in mind that you don’t need to install any software to do that.
1. Right-click on the Start Menu icon and select “Device Manager”.
2. Locate and click on “Mice and other pointing devices”.
3. Right-click on “ASUS touchpad” and select “Disable device” from the menu.
4. Click on the “Yes” button to apply your setting.