Remove form onSuccess

HTML

<script src="//app-sj01.marketo.com/js/forms2/js/forms2.min.js"></script>
<form id="mktoForm_96"></form>
<script>MktoForms2.loadForm("//app-sj01.marketo.com", "410-XOR-673", 96,
    function(form) {   
            form.onSuccess(function(form){
                formElem = this.formElem[0];
                formParent = formElem.parentNode;
                formParent.removeChild(formElem);
                formParent.innerHTML = 'All gone!';    
            });
    });
</script>