param(
  [string]$Path,
  [int]$Days
)
Join-Path (Split-Path $Path) "*.blg"
$limit = (Get-Date).AddDays(-$Days)

Get-ChildItem -Path $Path -File |
Where-Object { $_.LastWriteTime -lt $limit } |
ForEach-Object {
  Write-Host "Deleting: $($_.FullName)"
  Remove-Item $_.FullName -Force
}

#Usage
# .\CleanupLog.ps1 -Path "C:\perflogs\Admin\HostLog\*.blg" -Days 30
# or
# .\CleanupLog.ps1 "C:\perflogs\Admin\HostLog\*.blg" 30