$site = 'Webapplication' # replace this by your site name (not case sensitive)
$process = Get-CimInstance Win32_Process -Filter "Name = 'iisexpress.exe'" | ? {$_.CommandLine -like "*/site:`"$site`"*" }
if($process -ne $null)
{
Write-Host "Trying to stop $($process.CommandLine)"
Stop-Process -Id $process.ProcessId
Start-Sleep -Seconds 1 # Wait 1 second for good measure
Write-Host "Process was stopped"
} else
{
Write-Host "Website was not running"
}