Many time during design and development of magento theme we require to
remove default top menu  bar of magento to do that we just have to add

<reference name=”header”>
<action method=”unsetChild”><alias>topMenu</alias></action>
</reference>

where we want to remove the top menu i.e if we have to update the layout
for the specified pages and have to just unset the the top menu from reference head

to remove top menu from all the pages just remove or comment the following lines

from page.xml pf your theme

 <block type=”core/text_list” name=”top.menu” as=”topMenu” translate=”label”>
                <label>Navigation Bar</label>
  </block>