Connect your phone to a PC via ADB and use this command: adb shell wm overscan left,top,right,bottom where left, top, right and bottom are the coordinates upto which your screen works properly.
For example, if my phone with a resolution of 480px × 854px, would have had this problem, I would write adb shell wm overscan 0,0,0,839 to disable 15px at the bottom of the screen.