using System.Collections;
using System.Collections.Generic;
using System.Globalization;
public static void Main()
XDocument doc = XDocument.Parse(@"<SENDLABEL LABELACTION=""PRINT"" NAMEINPRINTER=""MLabel1"" PRINTERVARIANT=""162-12L"" FORMAT=""LEGACY"" PRINTTOFILEPATH=""""><TABLE NAME=""PARAMVALUE""><ROWDATA><ROW PARAM=""MAXGRAPHICCOMPRESSION"" VALUE=""0""/><ROW PARAM=""BARCODELABELSEQNOLEN"" VALUE=""0""/><ROW PARAM=""LABELROTATION"" VALUE=""0""/><ROW PARAM=""BARCODEGLOBALSEQNOLEN"" VALUE=""0""/><ROW PARAM=""PRINTAMOUNT"" VALUE=""1""/><ROW PARAM=""LABELLOCATION"" VALUE=""0""/><ROW PARAM=""CHARACTERMODE"" VALUE=""ASCII""/></ROWDATA></TABLE><TABLE NAME=""PLSAREA""><ROWDATA><ROW PLSETUPNO=""11217"" PRINTERAREA=""0""/></ROWDATA></TABLE><TABLE NAME=""PLSCHAN""><ROWDATA><ROW PLSETUPNO=""11217"" PRINTERAREA=""0"" CHANNELINDEX=""0"" HORIZONTALDPI=""304"" VERTICALDPI=""304"" RASTER=""0""/></ROWDATA></TABLE><TABLE NAME=""PLSETUP""><ROWDATA><ROW LABELHEIGHT=""795"" LABELWIDTH=""580,147""/></ROWDATA></TABLE> </SENDLABEL>");
Console.WriteLine(doc.Descendants("TABLE").Count());
var rows = doc.Descendants("ROW")
.Where(e=> e.Attribute("LABELHEIGHT") != null);
foreach (XElement e in rows)
Console.WriteLine( e.Attribute("LABELHEIGHT").Value);
rows.First().Attribute("LABELHEIGHT").Value = "";