Problem with session

[eluser]spagi[/eluser]
Hi, how can i delet only one item from user data array ?
Can anybody help?
I am trying :

Code:

$bas=$this->session->userdata('basket');
      $c=$this->uri->segment(3);


    $this->session->unset_userdata($bas[$c]);

but it does not work :-S

print_r($bas) = Array ( [0] => Array ( [name] => maxbike-lakone [table] => kola [varianta] => 22 [num] => 1 ) [1] => Array ( [name] => maxbike-belize-lady [table] => kola [varianta] => 18 [num] => 1 ) )