(# The bracket content below is alternative.)  

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"   xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:pat="http://schemas.xmlsoap.org/soap/envelope" 
xmlns="http://schemas.xmlsoap.org/soap/envelope"
version="1.0" >
   <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" />
   <xsl:strip-space elements="*" />
   <xsl:template match="@*|node()">
      <xsl:copy>
         <xsl:apply-templates select="@*|node()" />
      </xsl:copy>
   </xsl:template>
   <xsl:template match="/soapenv:Envelope">
      <xsl:copy>
        <soapenv:Header/>
            <soapenv:Body>
                <pat:getTradeMarksByApplicationNo>
                    <xsl:copy-of select="//*[local-name() = 'applicationNo']"/>
					<pat:arg0><xsl:copy-of  select="//*[local-name() = 'arg0']/text()" /></pat:arg0> 
                    <pat:userName>userName</pat:userName>
                    <pat:passWord>passWord</pat:passWord>
                    <pat:requester>requesterName</pat:requester>
                </pat:getTradeMarksByApplicationNo>
            </soapenv:Body>
      </xsl:copy>
   </xsl:template>
 
<xsl:template match="soapenv:Header" />

(#or

<xsl:template match="/S:Envelope/S:Header">
	<xsl:copy-of  select="/S:Envelope/S:Header" />
</xsl:template>
)
</xsl:stylesheet>
XML