You can modify the view in which you want to disable the 'All day event' field.
You can do it with the following steps.
1.Choose the view you want to modify from the views dropdownlist in the toolbar.
2.After the view is displayed you select the 'Modify the view' from the same dropdownlist.
3.Uncheck the 'All day event' field in the columns section and clcik the 'OK' button.