public static bool ResetPassword(string userName, string newPassword, HttpContext context,
  bool ExpirePassword = false)
{
  var manager = context.GetOwinContext().GetUserManager<myUserManager>();

  var user = manager.FindByName(userName);
  if (user == null)
     return false;

  var code = manager.GeneratePasswordResetTokenAsync(user.Id).Result;
  var result = manager.ResetPassword(user.Id, code, newPassword);
  if (result.Succeeded)
  {
    if (ExpirePassword)
    {
       user.PasswordToReset = true;
       manager.Update(user);
    }

       return true;
  }
  else
   return false;
}