How can I turn Turkish chars to ASCII? (like `ş` to `s`)

I tried replace but it didn't do anything.
Here is my code:

```
$posta = $posta.ToLower()
$posta = $posta -replace "ü","u" 
$posta = $posta -replace "ı","i"
$posta = $posta -replace "ö","o"
$posta = $posta -replace "ç","c"
$posta = $posta -replace "ş","s"
$posta = $posta -replace "ğ","g"
$posta = $posta.trim()
write-host $posta

```

if `$posta` was `eylül` it returns `eylül`