session_regenerate_id() would not change any state, so it's use is senseless here.
i still don't know,when to use unset( ) a session,or session_destroy();
if you want to destroy only one session variable, use unset.
if you want to destroy whole session with all variables, you must destroy a session
in this case, as Raju mentioned above, you should destroy the session and reload the page:
and you'll never see any of your session variables again
what is the use of "unset a particular session variable"?
same use as any other variable. when you no more need this particular variable
you can have more than one session variable