just write session["name"]=null;

session.abandont

using
session.abandon method

Session.RemoveAll();

by using session.kill()

by using session.abandon()
this cancels the current session immediately and releases 
all memory it occupied

session.abandon();

there are two ways to kill the session
1:abandon method
2:don't write anything in session it will automatically
kill

You can use 
Session.Abandon();
Or 
Session.RemoveAll();
or 
Session.Clear();

But it is better to use Session.Abandon()
because it will removes associated session is also

http://prajeeshkk.blogspot.com/
http://dotnetbird.wordpress.com/

There is nothing like Session.Kill in ASP.NET. So please 
update this. Best answer is Session.Abandon

We can use these to clear session
Session.Abandon();
this.sessio.clear();