How to delete element from array in php?

unset should work, you can also try this:

$array = array_merge(
             array_slice($array, 0, $index),
             array_slice($array, $index+1)
         );

You need to either remove it and remove the empty array:

function remove_empty($ar){
    $aar = array();
    while(list($key, $val) = each($ar)){
        if (is_array($val)){
            $val = remove_empty($val);
            if (count($val)!=0){
                $aar[$key] = $val;
            }
        }
        else {
            if (trim($val) != ""){
                $aar[$key] = $val;
            }
        }
    }
    unset($ar);
    return $aar;
}

remove_empty(array(1,2,3, '', 5)) returns array(1,2,3,5)

unset($array[$index]); actually works.
The only issue I can think of is the way you're iterating this array.
just use foreach instead of for

also make sure that $index contains correct value

to test your array you can use var_dump():

$cars[0]="Volvo"; 
$cars[1]="BMW"; 
$cars[2]="Toyota"; 

unset($cars[0]);
var_dump($cars);

If you want to delete just one array element you can use unset() or alternative array_splice()

Unset()
Example :

Code

<?php

    $array = array(0 => "x", 1 => "y", 2 => "z");
    unset($array[1]);
    //If you want to delete the second index ie, array[1]
?>

Output

Array (
    [0] => a
    [2] => c
)