Hello,
Nope, unfortunately, there is no option to disable the image there. But you can upload a white image for the subcategory by editing the subcategory http://prntscr.com/pg3i50 and manage the design of the categories/subcategories via Theme Options > WooCommerce > Shop elements > Categories > Categories Style (Classic for example to get title below the image) & Text Vertical Align to change the vertical position of the categories title.
Regards