[CmdletBinding()]
param(
    [int]$OlderThan=7
)

## Create a new timespan to compare with last write date of the target directory
$timedelta = New-TimeSpan -Days $OlderThan

## Remove all files and directories 
Foreach ( $item in (Get-ChildItem -Path "${Env:WinDir}\TEMP") ) {

    ## If it's older than the number of days specified, recursively delete the directory
    If ( $item.LastWriteTime -lt ((Get-Date) - $timedelta) ) { Remove-Item $item.FullName -Recurse -ErrorAction SilentlyContinue -Force }

}