Remove Key or Data from Associative array: PHP

<?php 
/*** remove key and data from associative array PHP */

$studentInfo =["name"=>"Tomy Jason","age"=>45,"sex"=>"Male"];
print_r($studentInfo);
  unset($studentInfo["sex"]);
echo "<br>";
print_r($studentInfo);

?>

Array ( [name] => Tomy Jason [age] => 45 [sex] => Male )
Array ( [name] => Tomy Jason [age] => 45 )