请根据您的要求尝试以下代码...

Please try below code for your requirement...

XDocument xmlDoc = XDocument.Load(filePath);
bool isExists = (from data in xmlDoc.Element("appsettings")
				select data).Any();
if (!isExists)
{
	    XmlElement parent = xmlDoc.CreateElement("configuration");
            //Now find that appSettings node and append it to parent Element
}

//Delete Node
XmlNodeList newXMLNodes = xmlDoc.SelectNodes("/configuration/appsettings");
foreach (XmlNode child in newXMLNodes)
{
  child.ParentNode.RemoveAll();
}