JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/knockout-validation/1.0.2/knockout.validation.min.js"></script>
<input type="text" data-bind="value: myObservable, valueUpdate: 'afterkeydown'"/>
<button data-bind="click: remove">Remove all validation</button>
<button data-bind="click: remove">Remove only required</button>

JavaScript

ko.validation.registerExtenders();
var vm = {
    myObservable: ko.observable("test").extend({required:true})
};
vm.remove = function() {
    vm.myObservable.extend({validatable: false});
}
vm.remove = function() {
    vm.myObservable.rules({validatable: false});
}
vm.removeRequired = function (){
    vm.myObservable.rules.remove(function (item) {
        return item.rule = "required";
    });
}

ko.applyBindings(vm)