Removing values from arrays

the following displays the pets array that was just created:
Array
(
    [0] => dragon
    [1] => unicorn
    [2] => tiger
    [3] => parrot
    [4] => scorpion
)

the following displays the pets array with the fifth element as an empty string:
Array
(
    [0] => dragon
    [1] => unicorn
    [2] => tiger
    [3] => parrot
    [4] => 
)

the following displays the pets array with the fifth element removed:
Array
(
    [0] => dragon
    [1] => unicorn
    [2] => tiger
    [3] => parrot
)