In the web.config add the following lines to system.web.

<webServices>
    <protocols>
        <remove name="Documentation" />
    </protocols>
</webServices>

If you want to allow certain types, use the “add” directive. Below lines
will allow GET and POST commands, but hides the operations.

<webServices>
    <protocols>
        <add name="HttpPost" />
        <add name="HttpGet" />
        <remove name="Documentation" />
    </protocols>
</webServices>

That’s all.