PowerShell - Delete item from array

There are several answers to this question, if $arr is a System.Array you would have to reconstruct it in order to remove the empty spaces. This is because this type is of a fixed size.

Some examples of how you could do that would be:

PS /> $arr = @(
    'A STRING'
    ' '
    'ANOTHER STRING'
    ' '
    'LAST STRING'
)

# Some examples:
$arr = $arr | Where-Object { -not [string]::IsNullOrWhiteSpace($_) }
# OR
$arr = $arr.Where({ ' ' -ne $_ })
# OR
filter RemoveWhiteSpace {
    if(-not [string]::IsNullOrWhiteSpace($_)){ $_ }
}

$arr = $arr | RemoveWhiteSpace
# And more...

PS /> $arr
A STRING
ANOTHER STRING
LAST STRING

Note, Where-Object is not the most efficient way of reconstructing the array but works fine for this example. If the array was much bigger, the most efficient way of filtering the collection would be:

PS /> $arr = @(
    'A STRING'
    ' '
    'ANOTHER STRING'
    ' '
    'LAST STRING'
)

$newArr = foreach($i in $arr)
{
    if(-not [string]::IsNullOrWhiteSpace($i))
    {
        $i
    }
}

PS /> $newArr
A STRING
ANOTHER STRING
LAST STRING

Supposing, $arr is of a dynamic type that allows addition and removal of elements, you could do it like this:

PS /> $arr = [System.Collections.ArrayList]@(
    'A STRING'
    ' '
    'ANOTHER STRING'
    ' '
    'LAST STRING'
)

$arr.RemoveAt('1') # Removes position 1, in turn 
$arr.RemoveAt('2') # 'ANOTHER STRING' is the new position 1

PS /> $arr
A STRING
ANOTHER STRING
LAST STRING

Or like this:

PS /> $arr = [System.Collections.ArrayList]@(
    'A STRING'
    ' '
    'ANOTHER STRING'
    ' '
    'LAST STRING'
)

$arr.Remove(' ')
$arr.Remove(' ')

PS /> $arr
A STRING
ANOTHER STRING
LAST STRING

You can find a lot more information on MS Docs.