If you don't want to use the touchscreen, then use the mouse and keyboard. There is no need to disable the touchscreen. I have a touchscreen on my laptop but I use a mouse and it never bothers me at all.
If you still want to disable the touchscreen see here:
https://support.microsoft.com/en-us/help/402801...
https://www.thewindowsclub.com/disable-touch-sc...
If the window middle Maximize button is missing it means you're in Tablet Mode. Switch out of Tablet Mode by pressing Windows key + A and toggling off Tablet Mode.
If that isn't enough then change the Theme in Settings > Personalization > Themes or from the many spectacular free Themes you can download from the Store to that control panel to choose from: https://www.microsoft.com/en-us/store/collectio.... This resets the display.
If that doesn't do it then try one of the other fixes here, but do not click on any ad links just follow the excellent editorial steps without clicking on anything: https://windowsreport.com/minimize-maximize-clo...