Radio button disabler (answer to http://softwarerecs.stackexchange.com/questions/13490/chrome-extension-to-eliminate-choices-on-multiple-choice-questions)

disabler.user.js

// ==UserScript==
// @name         Input Disabler
// @namespace    http://stackexchange.com/users/4337810/%E1%B9%A7%D0%BD%CA%8A%C3%9F
// @version      0.1
// @description  This script allows you to disable any HTML inputs you find across the web!
// @author       ṧнʊß (shub)
// @match        http://*/*
// @match        https://*/*
// ==/UserScript==

 function addButtonBefore(inputItem) {
     var button = document.createElement("button");
     var text = document.createTextNode("eliminate");
     button.appendChild(text);
     cssString = "font-size: 9px; border: 0; border-radius: 10px; outline: none;"
     button.style.cssText = cssString;
     button.setAttribute("title", "disable / enable this element")
     button.addEventListener('click', function(e) {
         var state = inputItem.disabled;
         inputItem.disabled = !state;
         e.preventDefault();
         e.stopPropagation();
         e.cancelBubble = true;
         e.returnValue = false;
         return false;
     });

     inputItem.parentNode.insertBefore(button, inputItem.nextSibling.nextSibling); //Doubled .nextSibling because some elements have text after them. Difference is unnoticeable for elements without text.
 }

 Array.prototype.forEach.call(document.getElementsByName('answer'), function(inputItem) {
     addButtonBefore(inputItem);
 });

This was specifically designed as an answer to this (on Software Recommendations Beta SE). It will work with radio buttons in a group called 'answer'. You can easily change this by changing line 31 answer to the radio button group name.