browser appilcation does not have much hold over client computer.. (it shouldn't have!!! otherwise we will lose all our valueable data!!!! :))
we can set expiery of the cookies which are created by our website (domain), but we can not remove it. follow the article on MSDN to do this.
http://msdn.microsoft.com/en-us/library/ms178195.aspx[
^]
We can set expirey of cache by following code
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetExpires(DateTime.Now.AddSeconds(-1));
Response.Cache.SetNoStore();
mark as answer if solves your problem.