JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div id="wrapper"><span>Some</span> content</div>
    <div>More content</div>
</div>

<button id="unwrap">Unwrap</button>

CSS

#container {
    border: 1px solid black;
    padding: 5px;
}

#wrapper {
    border: 2px solid red;
    padding: 5px;
}

JavaScript

function unwrap(element) {
    // insert all the element's children *after* the element itself
    var parent = element.parentNode;
    var children = element.childNodes;
    var before = element.nextSibling;

    // reverse iteration always inserting the previous sibling before
    // the next one
    for (var i = children.length - 1; i > -1; i--) {
        before = parent.insertBefore(children[i], before);
    }

    // remove the element
    parent.removeChild(element);
}

document.getElementById('unwrap').onclick = function() {
    var element = document.getElementById('wrapper');
    if (element) {
        unwrap(element);
    }
};