JSFiddle - React, Tailwind, and code Playground

HTML

First name:
<input type="text" id="firstname">
<br>
<p>Your first name is: <b id='boldStuff2'></b> 
</p>
<p>Other people's names:</p>
<ol id="demo"></ol>
<input type='button' onclick='changeText2()' value='Submit' />
<input type='button' onclick='alert(getNames())' value='Alert Names' />

JavaScript

var list = document.getElementById('demo');
var lastid = 0;

function changeText2() {
    var firstname = document.getElementById('firstname').value;
    document.getElementById('boldStuff2').innerHTML = firstname;
    var entry = document.createElement('li');
    entry.appendChild(document.createTextNode(firstname));
    entry.setAttribute('id','item'+lastid);
    entry.setAttribute('data-name',firstname); //added a data-name attribute for easier access to name
    var removeButton = document.createElement('button');
    removeButton.appendChild(document.createTextNode("remove"));
    removeButton.setAttribute('onClick','removeName("'+'item'+lastid+'")');
    entry.appendChild(removeButton);
    lastid+=1;
    list.appendChild(entry);
}


function removeName(itemid){
    var item = document.getElementById(itemid);
    list.removeChild(item);
}

function getNames(){
    var names = [];
    for(var i=0;i<list.children.length;i++){
        names.push(list.children[i].getAttribute("data-name"));//get previously set attribute and add to array
    }
    return names;
}