<configuration>

<system.web>

<sessionState mode="Off|InProc|StateServer|SQLServer"

              cookieless="true|false"

              timeout="number of minutes"

              stateConnectionString="tcpip=server:port"

              sqlConnectionString="sql connection string"

              stateNetworkTimeout="number of seconds"/>

</configuration>

</system.web>

Set the sessionState mode=”Off” in web.config file to off the session state.

Off Indicates that session state is not enabled.
InProc Indicates that session state is stored locally.
StateServer Indicates that session state is stored on a remote server.
SQLServer Indicates that session state is stored on the SQL Server.

Section of web.config, you should locate the httpmodule tag and you simply disable session by doing a remove tag with attribute name set to session.

<httpModules>

<remove name=”Session” />