You may run into a rare case of needing to unselect a radio button. Here’s how you can do this in javascript.

let allTheRadios = document.getElementsByName('thenameyougavetheradiobuttons'); 
let currentRadio;
for(x = 0; x < allTheRadios.length; x++){
    allTheRadios[x].onclick = function() {
        if(currentRadio === this){
            this.checked = false;
            // do something here when it's unchecked if you want to
            currentRadio = null;
        } else {
            currentRadio = this;
        }
    };
}