webservice 序列化 获取类结构XML的问题

请教下，我定义的了两个实体类，经过序列化 获取xml的格式如下 ，有两个节点地方要去除 。请问在代码中怎么去除
输出
<?xml version="1.0" encoding="UTF-8"?>
<string ---要去除
xmlns="http://tempuri.org/">
<Response>
<ResultCode>0</ResultCode>
<ResultContent>数据获取成功</ResultContent>
<Data>
<EUSERINFO>---要去除
<Name>张医生</Name>
<Dept>门诊部</Dept>
<BM>1001</BM>
</EUSERINFO>
</Data>
</Response>
</string>

结构
public class Response
{

[System.Xml.Serialization.XmlElement(IsNullable = true)]
[DataMember]
public string ResultCode { get; set; }
[DataMember]
public string ResultContent { get; set; }
[DataMember]
public List<EUSERINFO> Data { get; set; }
}
public class EUSERINFO
{

[System.Xml.Serialization.XmlElement(IsNullable = true)]
[DataMember]
public string Name { get; set; }
[System.Xml.Serialization.XmlElement(IsNullable = true)]
[DataMember]
public string Dept { get; set; }
[System.Xml.Serialization.XmlElement(IsNullable = true)]
[DataMember]
public string BM { get; set; }

}

public string XmlSerialize<T>(T obj)
{
XmlSerializer xs = new XmlSerializer(obj.GetType());
MemoryStream ms = new MemoryStream();
//设置序序化XML格式
XmlWriterSettings xws = new XmlWriterSettings();
xws.Indent = true;
xws.OmitXmlDeclaration = true;
xws.Encoding = Encoding.UTF8;

using (XmlWriter xtw = XmlTextWriter.Create(ms, xws))
{

XmlSerializerNamespaces _namespaces = new XmlSerializerNamespaces(
new XmlQualifiedName[] {
new XmlQualifiedName(string.Empty,string.Empty)
});
xs.Serialize(xtw, obj, _namespaces);
ms.Position = 0;
xtw.Close();
}
byte[] b = ms.ToArray();
string s = System.Text.Encoding.UTF8.GetString(b, 0, b.Length);
return s;

}