... in admin/images.php find ...
show_user_select_row($lang['user'], $image_row['user_id']);
... to remove : replace with ...
//show_user_select_row($lang['user'], $image_row['user_id']);
... to show only the User-ID : replace with ...
//show_user_select_row($lang['user'], $image_row['user_id']);
show_input_row("User ID", "user_id", $image_row['user_id']);
... thats all ...