$ftpServer = "RandomFTPServer"
$ftpUser = "Username"
$ftpPassword = read-host "Password"-AsSecureString

$credentials=New-ObjectSystem.Net.NetworkCredential($ftpUser,$ftpPassword)

function Get-FtpRequest($ftpPath){
    $ftpRequest = [System.Net.FtpWebRequest]::create("$ftpServer/$ftpPath")
    $ftpRequest.Credentials =  $credentials
    $ftpRequest.UseBinary = $true
    $ftpRequest.KeepAlive = $true
    $ftpRequest.UsePassive=$true
    return $ftpRequest
}

# Load WinSCP .NET assembly
Add-Type -Path "WinSCPnet.dll"

# Setup session options
$sessionOptions = New-Object WinSCP.SessionOptions -Property @{
    Protocol = [WinSCP.Protocol]::Ftp
    HostName = "ftp.example.com"
    UserName = "user"
    Password = "mypassword"
}

try
{
    # Connect
    $session = New-Object WinSCP.Session
    $session.Open($sessionOptions)

    # List files
    $remotePath = "/remote/path"
    $directoryInfo = $session.ListDirectory($remotePath)

    # Find old files
    $limit = (Get-Date).AddDays(-15)

    $oldFiles =
        $directoryInfo.Files |
        Where-Object { -Not $_.IsDirectory } |
        Where-Object { $_.LastWriteTime -lt $limit }

    # Delete them
    foreach ($oldFileInfo in $oldFiles)
    {
        $session.RemoveFiles($session.EscapeFileMask($remotePath + "/" + $oldFileInfo.Name)).Check()
    }

    Write-Host "Done"
}
finally
{
    # Disconnect, clean up
    $session.Dispose()
}