С рекурсивным обходом папок
$now = Get-Date
$date = $now.AddMonths(-1)
$files = Get-ChildItem -Path C:\Log -recurse | Where {$_.LastWriteTime -le "$date"}
foreach ($file in $files) {
write-host "Deleting File $file" -foregroundcolor "Red";
Remove-Item $file # для теста добавить -whatif
}
gci ‘E:\IIS Logs’ -Directory | gci -Include ‘*.log’,’*.blg’ -Recurse | ? LastWriteTime -lt (Get-Date).AddDays(-30) | Remove-Item