soap envolop writting in c#

Question

i am using this code
XmlElement soapbody = xmlDoc.CreateElement("SOAP-ENV", "Body", "http://www.ebxml.org/namespaces/messageHeader");
soapbody.RemoveAllAttributes();
xmlDoc.DocumentElement.PrependChild(soapbody);
it return this result
<SOAP-ENV:Header xmlns:SOAP-ENV="http://www.ebxml.org/namespaces/messageHeader" />
but i want
<SOAP-ENV:Header  />
how remove
 xmlns:SOAP-ENV="http://www.ebxml.org/namespaces/messageHeader"
plz tell