The best way to reduce height of a full width slider in divi, is to add the following custom css to the Custom CSS field of epanel > general settings:

#testslide .et_pb_slide_description {
padding: 70px 0 !important;
}
#testslide .et_pb_slider, .home .et_pb_slides, .home .et_pb_slide {
height: 480px;
}  

The add the css id: testslide to your module as pictured below. 

]