Three solutions:
1. Removing header image from .html files.
ow_themes/showcase/master_pages/general.html
Remove or comment out following line:
<div class="ow_header_pic"></div>
2. Hiding header image using CSS.
admin panel>>appearance>>edit theme>>"CSS" tab.
Adjust "height" property in following styles to fit your needs ( make header image smaller in height or "hide" it completely by setting height to zero):
.ow_header_pic {
height: 325px;
background-image: url('images/header.jpg');/** OW_Control type:image, key:headerImage, section:1. General Settings, label: Page header image **/
background-repeat: no-repeat;
}
3. Same place as in solution #2.
But you can just completely remove
background-image