C# remove nodes listed into XmlNodeList from XML file

it's my first post here ^^,

I have a problem with my XML file.

 <?xml version="1.0" encoding="UTF-8"?>
   <config>
    <settings>
     <excelFilePath>C:\Temp\</excelFilePath>
     <mailHost>smtp</mailHost>
     <mailPort>25</mailPort>
     <mailFrom>me@test.com</mailFrom>
     <keepInCopy>
         <mailCC>email1@test.com</mailCC>
         <mailCC>email2@test.com</mailCC>
         <mailCC>email3@test.com</mailCC>
    </keepInCopy>
    <mailSubject>My Mail subject</mailSubject>
    <mailBodyPath>Templates\Template1.htm</mailBodyPath>
    </settings>
 </config>

In practice i just need to delete all tags . I'm currently trying this C# code, but nothing happens:

XmlDocument xml = new XmlDocument();
xml.Load(FilePath);

XmlNodeList xnList = xml.GetElementsByTagName(xmlTag);
foreach (XmlNode xn in xnList)
{
    xn.RemoveChild(xn.FirstChild);
    xml.Save(FilePath);
}

Could you help me please?