How do you unregister snippets in Ace Editor?

Question

I can register the snippets...

var editor = ace.edit("editor");
var snippetManager = ace.require("ace/snippets").snippetManager;
var snippetText = "snippet vfx\n\t<visalforce>\n\t\t$1\n\t</visalforce>";
var snippets = snippetManager.parseSnippetFile(snippetText);
snippetManager.register(snippets);

editor.setOptions({
    enableBasicAutocompletion: true,
    enableSnippets: false
});

But, the unregister just does not work and there is almost zero documentation or samples on the inter-webs...but I keep trying variations of this...

snippetText = "snippet vfx\n\t<visalforce>\n\t\t$1\n\t</visalforce>";
snippets = snippetManager.parseSnippetFile(snippetText);
snippetManager.unregister(snippets);

And it does not work. The snippets are still available in the editor.