Troubles with substring, trim, trimend - powershell

Question

I'm trying to take an array of email addresses (in the form of username#company.com) which is generated from:
$users = get-MSOLUser -All | where {$_.isLicensed -eq "TRUE" -and $_.Licenses.AccountSKUID -eq "my_license"} | select userprincipalname
And get just the username from each. I start with username#company.com and want to end up with username. I have tried various ways using substring, Trim, TrimEnd, etc and can't get any of them working.
$username = $users | %{$_.substring(0,$users.length - 12)}
$users | %{$_.trimend("#company.com")}
$users | %{$_.trimend(12)}
All of the above give errors including the two below.
Method invocation failed because [Selected.Microsoft.Online.Administration.User] does not
contain a method named substring.
Method invocation failed because [Selected.Microsoft.Online.Administration.User] does not
contain a method named trimend.
What am I doing wrong with the syntax, or is there something else, like a module I haven't imported, or how my syntax is trying to work with an array?

Answer 1

This will return you a list of all usernames (without domain) that fulfills your conditions:
$users = Get-MSOLUser -All |
Where-Object {$_.isLicensed -eq "TRUE" -and $_.Licenses.AccountSKUID -eq "my_license"} |
ForEach-Object { $_.userprincipalname -replace '#.*' }

Answer 2

Well, you need to work with the property, not with the object, so you would probably want to do something like:
select -expandproperty userprincipalname
but that would create an array of userprincipalnames, so no other attributes.
When you run get-MSOLUser you get back an object, with a bunch of properties. When you do select -expandproperty you are getting back only certain property, but not an object itself. You are getting back a system.string object. And that object has all those methods you are trying to invoke.