Remove format field as it's the one for grading type.

cms/templates/edit_subsection.html

@@ -23,10 +23,6 @@
           <label>Display Name:</label>
           <input type="text" value="${subsection.display_name}" class="subsection-display-name-input" data-metadata-name="display_name"/>
         </div>
-        <div>
-          <label>Format:</label>
-          <input type="text" value="${subsection.metadata['format'] if 'format' in subsection.metadata else ''}" class="unit-subtitle" data-metadata-name="format"/>
-        </div>
         <div class="sortable-unit-list">
           <label>Units:</label>
           ${units.enum_units(subsection, subsection_units=subsection_units)}