Disable "Download Document"

I'm not sure what you mean by the right click menu as I'm not seeing download *there*, but you can disable by using showDownloadPDF:false. Sample code generated by our Embed demo (https://documentcloud.adobe.com/view-sdk-demo/index.html#/customize/FULL_WINDOW/Bodea%20Brochure.pdf)

<div id="adobe-dc-view"></div>
<script src="https://documentcloud.adobe.com/view-sdk/main.js"></script>
<script type="text/javascript">
	document.addEventListener("adobe_dc_view_sdk.ready", function(){ 
		var adobeDCView = new AdobeDC.View({clientId: "<YOUR_CLIENT_ID>", divId: "adobe-dc-view"});
		adobeDCView.previewFile({
			content:{location: {url: "https://documentcloud.adobe.com/view-sdk-demo/PDFs/Bodea Brochure.pdf"}},
			metaData:{fileName: "Bodea Brochure.pdf"}
		}, {showDownloadPDF: false});
	});
</script>