Remove NTFS permissions of a user in all sub-directories - powershell

Question

I am writing a PowerShell script which would delete a specific user from all sub-directories.
Below script only removes the permission from the folder but I want to remove permission from all sub-folders as well.
$acl = get-acl c:\temp
$accessrule = New-Object System.Security.AccessControl.FileSystemAccessRule ("domain\user","Read",,,"Allow")
$acl.RemoveAccessRuleAll($accessrule)
Set-Acl -Path "c:\temp" -AclObject $acl

Answer 1

You are only setting the acl of the root folder. Set-Acl by itself does not allow you to propagate to subfolders.
Note that that might not be what you want anyway. You want to remove a rule from all folders instead of replacing the acls on all subfolders with the acl of your root folder.
Safer would be to get the acl of each subfolder, remove the rule and set the acl of each subfolder.
icaclscudo's to Ansgar might be better for this task. A Powershell way might be as follows
$accessrule = New-Object system.security.AccessControl.FileSystemAccessRule("domain\user","Read",,,"Allow")
$root = 'c:\temp'
#(Get-Item $root) + #(Get-ChildItem $root -Recurse -Directory) | Foreach-Object {
$acl = Get-Acl $_.FullName
$acl.RemoveAccessRuleAll($accessrule)
Set-Acl $_.FullName -AclObject $acl -WhatIf
}

Answer 2

$Path = "c:\temp\"
$User = "admin"
$Account = new-object system.security.principal.ntaccount($User)
$ACL = Get-Acl -path $Path
$ACL.PurgeAccessRules($Account)
$ACL | Set-Acl -path $Path -Verbose
gci -Recurse -Path $Path -Directory | %{
$ACL = Get-Acl -path $_.FullName
$ACL.PurgeAccessRules($Account)
$ACL | Set-Acl -path $_.FullName -Verbose
}