C#

private string PGM_StripNamespaces(string xml)
{
	XmlTextReader reader = new XmlTextReader(new StringReader(xml));
	MemoryStream outputStream = new MemoryStream();
	XmlTextWriter writer = new XmlTextWriter(outputStream, new System.Text.UTF8Encoding(false));
	writer.WriteStartDocument();

	while(reader.Read())
	{
		switch(reader.NodeType)
		{
			case XmlNodeType.Element:
				writer.WriteStartElement(reader.Name);

				if(reader.HasAttributes)
				{            
					//Cannot just use writer.WriteAttributes, 
					// else it will also emit xmlns attribute               
					while(reader.MoveToNextAttribute())
					{
						if(reader.Name.CompareTo("xmlns") != 0)
							writer.WriteAttributeString(reader.Name,reader.Value);
					}
					reader.MoveToElement();              
				}
				if(reader.IsEmptyElement)
				{
					writer.WriteEndElement();
				}
				break;
			case XmlNodeType.Text:
				writer.WriteString(reader.Value);
				break;
			case XmlNodeType.CDATA:
				writer.WriteCData(reader.Value);
				break;
			case XmlNodeType.ProcessingInstruction:
				writer.WriteProcessingInstruction(reader.Name,reader.Value); 
				break;
			case XmlNodeType.Comment:
				writer.WriteComment(reader.Value); 
				break;      
			case XmlNodeType.EntityReference:
				writer.WriteEntityRef(reader.Name); 
				break;
			case XmlNodeType.EndElement:
				writer.WriteEndElement();
				break;
		}
	}
	writer.WriteEndDocument();
	writer.Flush();
	writer.Close();
	reader.Close();

	return System.Text.Encoding.UTF8.GetString(outputStream.ToArray());
}

<xsl:stylesheet xmlns:xsl ="http://www.w3.org/1999/XSL/Transform" version ="1.0" >
	<xsl:template match ="@*" >
		<xsl:attribute name ="{local-name()}" >
			<xsl:value-of select ="." />
		</xsl:attribute>
		<xsl:apply-templates/>
	</xsl:template>
	<xsl:template match ="*" >
		<xsl:element name ="{local-name()}" >
			<xsl:apply-templates select ="@* | node()" />
		</xsl:element>
	</xsl:template>
</xsl:stylesheet> 

private string XSL_StripNamespace(string xml)
{
	//Create a new XslTransform object.
	XslTransform xslt = new XslTransform();

	//Load the stylesheet.
	//XSLT is a class property that returns a string containing the XSL transform
	XmlTextReader reader = new XmlTextReader(new StringReader(XSLT));
	xslt.Load(reader, null, null);

	//Create a new XPathDocument and load the XML data to be transformed.
	XPathDocument mydata = new XPathDocument(new StringReader(xml));

	//Create an XmlTextWriter which outputs to the console.
	MemoryStream outputStream = new MemoryStream();
	XmlTextWriter writer = new XmlTextWriter(outputStream, new System.Text.UTF8Encoding(false));

	//Transform the data and send the output to the console.
	xslt.Transform(mydata,null,writer, null);

	return System.Text.Encoding.UTF8.GetString(outputStream.ToArray());
}