Introduction
Solution
You can do it easily with XDocument
var xDocument = XDocument.Parse(@"<configuration>
<property>
<name>name</name>
<value>dinesh</value>
</property>
<property>
<name>city</name>
<value>Delhi</value>
</property>
</configuration>");
var firstPropertyElement = xDocument
.Descendants("property")
.First();//Find your element
var xComment = new XComment(firstPropertyElement.ToString());//Create comment
firstPropertyElement.ReplaceWith(xComment);//Replace the element with comment
Console.WriteLine(xDocument);
Which outputs:
<configuration>
<!--<property>
<name>name</name>
<value>dinesh</value>
</property>-->
<property>
<name>city</name>
<value>Delhi</value>
</property>
</configuration>