Enable and disable client-side validation in ASP.NET MVC

In your project config file add below keys:

<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />

Or if you want to set this programmatically then do below code in Application_Start()

void Application_Start(object sender, EventArgs e)
{     
     HtmlHelper.ClientValidationEnabled = true;
     HtmlHelper.UnobtrusiveJavaScriptEnabled= true;
}