Question: Is there a way to disable multi select?

Answer: 
Remove the `muiltiple="multiple"` in the following line:

```
<select id="id" name="name" multiple="multiple">

```

So, it is as good as removing that attribute. I'd use jQuery.
Regarding your question, disable to multiple select is quite simple? Isn't it?

```
<select multiple="multiple" disabled = "true">
    <option value="1"> One
    <option value="2"> Two
    <option value="3"> Three        
</select>

```