I use this:
public static string RemoveAccents(this string accentedStr)
{
byte[] tempBytes = Encoding.GetEncoding("ISO-8859-8").GetBytes(accentedStr);
return Encoding.UTF8.GetString(tempBytes, 0, tempBytes.Length);
}
Edit: this solution works in Windows 8 apps, but not in Windows Phone. The best solution I have found so far is this manual one:
http://invokeit.wordpress.com/2011/10/06/how-to-remove-diatrics-accent-marks-in-windows-phone-7-x/