RemoveDiacritics.cs

static string RemoveDiacritics(this string text)
{
    Encoding srcEncoding = Encoding.UTF8;
    Encoding destEncoding = Encoding.GetEncoding(1252);

    text = destEncoding.GetString(Encoding.Convert(srcEncoding, destEncoding, srcEncoding.GetBytes(text)));

    string normalizedString = text.Normalize(NormalizationForm.FormD);
    StringBuilder result = new StringBuilder();

    for (int i = 0; i < normalizedString.Length; i++)
    {
        if (!CharUnicodeInfo.GetUnicodeCategory(normalizedString[i]).Equals(UnicodeCategory.NonSpacingMark))
        {
            result.Append(normalizedString[i]);
        }
    }

    return result.ToString();
}