To remove a custom resolution for your HDTV display
Note: You must be an advanced user and have knowledge of display timing concepts in order to work with custom timings for your display.
From the NVIDIA Control Panel navigation tree pane, under Display, click Change resolution.
Click the image that represents the display you want to affect.
Click Customize, then check the Enable resolutions not exposed by the display check box.
From the list that appears in the Resolutions box, select the custom resolution you want to remove.
Click the Delete icon or press Delete on your keyboard.
Repeat steps 4 and 5 for each custom resolution you want to remove.