Remove matching collection object from text file - string

Question

I have a list of users that I am storing in a text file. I am trying to update the text file so it removes any user that match $NotExpiring users variable, which is a collection. I just can't figure out how I would update the text file properly if more than one user needs to be removed from text file.
Below is the full function. You can ignore most of it Just look under #Stuck Here to get to the point.
function Get-NotExpiring{
$NotExpiring=New-Object System.Collections.Generic.List[System.Object]
$MatchedUser=New-Object System.Collections.Generic.List[System.Object]
$textfiles = Get-ChildItem $email_dir
#Day of Span
$Days="20"
#Settings
$Date=Get-Date ((Get-Date).adddays($Days))
$Users=Get-ADUser -filter {(Enabled -eq $True) -and (PasswordNeverExpires -eq $False)} -Properties SamAccountName, DisplayName, msDS-UserPasswordExpiryTimeComputed, Mail | Where-Object { $_.DisplayName -ne $nul -and ($_."msDS-UserPasswordExpiryTimeComputed" -gt ($NotExpDate.ToFileTime()))} | Select SamAccountName, Mail, DisplayName,#{Name="ExpiryDate";Expression={([datetime]::fromfiletime($_."msDS-UserPasswordExpiryTimeComputed")).DateTime}}
#Magic
foreach ($Entry in $Users) {
$EntryDate = Get-date($Entry.ExpiryDate)
if ($EntryDate -gt $Date){
$Account = $Entry.SamAccountName
$ExpDate = $Entry.ExpiryDate
$NotExpiring.add($Account)
}
}
#STUCK HERE
foreach($file in $textfiles){
foreach ($user in $NotExpiring){
if((Get-Content "$email_dir\$file") -contains $user){
$temp_get = Get-Content $email_dir\$file | where {$_ -notmatch $user}
}}}
$temp_get}
I tried below but it doesn't seem to work if more than one user are $NotExpiring that are also in the existing textfile. Any help would be appreciated. I know this is a simple fix but I can't seem to figure it out.
Get-Content $email_dir\$file | where {$_ -notmatch $user} | Set-Content <path>.txt
I was able to achieve exactly what I needed using the following solution.
foreach($file in $textfiles){ foreach ($user in $NotExpiring){
if((Get-Content "$email_dir\$file") -contains $user){
$MatchedUser.add($user)
}}
Get-Content "$email_dir\$file" | Where {$MatchedUser -NotContains $_ } | Set Content "$temp_dir\$file"
Copy-Item -path "$temp_dir\$file" -Destination "$email_dir\$file" -ErrorAction SilentlyContinue }

Answer 1

Basicly you are trying to match two arrays.
With where you do it foreach object. Now you have to match the single object $_ with the array $user.
Use:
...| where {$_ -notin $user}
or
...| where {$user -notcontains $_}