@Html.Raw(Model.MyHtml)

public ActionResult Save(MyModel model)
{
    if (HasScripts(model.MyHtml)
    {
        ModelState.AddModelError("MyHtml", "The html cannot contain script tags");
    }
    if (!ModelState.IsValid)
    {
        return View(model);
    }
    // save and redirect
}

public bool HasScripts(string html)
{
    HtmlDocument document = new HtmlDocument();
    document.LoadHtml(html);
    HtmlNode root = document.DocumentNode;
    return root.Descendants("script").Any();
}

public string RemoveScripts(string html)
{
    HtmlDocument document = new HtmlDocument();
    document.LoadHtml(html);
    HtmlNode root = document.DocumentNode;
    IEnumerable<HtmlNode> scripts = root.Descendants("script");
    for(int i = 0; i < scripts.Count(); i++)
    {
        HtmlNode script = scripts[i];
        script.Remove();
    }
    return scripts.Any() ? document.ToString() : html;
}

model.MyHtml = RemoveScripts(model.MyHtml);