powershell, replace an Array object with nothing

I need to get rid of an object ($deletehostname) in an array and have the following code:

if ($BackConnectionHostnamesExists)
{
$zero=""		
$ExistingHostnames = ($BackConnectionHostnamesExists.BackConnectionHostnames)
$ExistingHostnames = $ExistingHostnames.replace($deletehostname, $zero)

Set-ItemProperty HKLM:\System\CurrentControlSet\Control\Lsa\MSV1_0 -Name "BackConnectionHostnames" -value $ExistingHostnames
}

$deletehostname is successfully removed, but it is replaced by an open line.

so if $deletehostname = test3, my result is:

test1

test2



test4

test5

I would love to get rid of that empty space! So is it possible to replace by nothing?

br

Bjorn