When we add protlet on the page it by default set visible.

Now, hide the portlet or set visible false using javascript.
For this you can combine your javascript approach with the parameter approach as follows:

<%
String paramFromRequestToHide = renderRequest.getParameter("hidePortlet");

if (paramFromRequestToHide .equals("YES")) {
%>

<aui:script>
    Liferay.Portlet.ready(

    /*
    This function gets loaded after each and every portlet on the page.

    portletId: the current portlet's id
    node: the Alloy Node object of the current portlet
    */
        function(portletId, node) {
            document.getElementById(portletId).style.display = 'none';
            // or alternatively using pure Alloy UI
            // node.hide();
        }
    );
</aui:script>

<%
} else {
%>

<aui:script>
    Liferay.Portlet.ready(
        function(portletId, node) {
            document.getElementById(portletId).style.display = 'block';
            // or alternatively using pure Alloy UI
            // node.show();
        }
    );
</aui:script>

<%
}
%>