JSFiddle - React, Tailwind, and code Playground

HTML

<button id="buttonAdd">Add another plan</button>
<button id="buttonRemove">Remove another plan</button>
<div id="duplicater" class="duplicater">
    <p>Choose Your Mobile Plan</p>
    <select>
        <option value="1">Package 1</option>
        <option value="2">Package 2</option>
        <option value="3">Package 3</option>
        <option value="4">Package 4</option>
        <option value="5">Package 5</option>
        <option value="6">Package 6</option>
    </select>
</div>

JavaScript

var buttonAdd = document.getElementById('buttonAdd');
var buttonRemove = document.getElementById('buttonRemove');
var original = document.getElementById('duplicater');

buttonAdd.onclick = duplicate;
buttonRemove.onclick = remove;

var min = 1;
var max = 5 + min;

function refresh() {
    var count = document.getElementsByClassName('duplicater').length;
    buttonAdd.disabled = count >= max;
    buttonRemove.disabled = count <= min;
}

function duplicate() {
    var count = document.getElementsByClassName('duplicater').length;
    if (count < max) {
        count++;
        var clone = original.cloneNode(true);
        clone.id = "duplicater" + count;
        original.parentNode.appendChild(clone);
        refresh();
    }
}

function remove() {
    var count = document.getElementsByClassName('duplicater').length;
    if (count > min) {
        var toRemove = document.getElementById('duplicater' + count);
        toRemove.parentNode.removeChild(toRemove);
        refresh();
    }
}

refresh();