/templates/default/icon_select.tpl

to NEVER have an option to select an icon and always default to blank.gif (ie no icon), just put this in the template (replace what's there)

HTML
<tr>
<td style="display:none;">Muhaha</td>
<td style="display:none;">
  <input type="hidden" name="Icon" value="blank.gif" />
</td>
</tr>