<div id="stepper"></div>
<script>
$("#stepper").kendoStepper({
    steps: [
        { label: "Step 1" },
        { label: "Step 2" },
        { label: "Step 3" }
    ]
});

var stepper = $("#stepper").data("kendoStepper");
var step = stepper.steps()[0];

// Disable the step
step.enable(false);
</script>