hiding SiteMapNode

Hi,
I would like to hide the dropdown navigation of a menu (Guidelines) and these are from Epidemiology onwards as per the code below. I'm not sure how to achieve this though and any help is grately appreciated.
Thanks

<siteMapNode url="~/Content/HCPS/Declaration.aspx" mtitle="HCPS" title="HCPS" description="HCPS" class="last"> <siteMapNode url="~/Content/HCPS/Guidelines.aspx" title="Guidelines" description="Guidelines" /> <siteMapNode url="~/Content/HCPS/Epidemiology.aspx" title="Epidemiology" description="Epidemiology" /> <siteMapNode url="~/Content/HCPS/SelfTherapy.aspx" title="Evidence for self-therapy" description="Evidence for self-therapy" /> <siteMapNode url="~/Content/HCPS/FurtherResources.aspx" title="Further resources for HCPs" ...