JSFiddle - React, Tailwind, and code Playground

HTML

<div id="myDiv" style="margin: 50px 50px 50px 50px">This is a div.</div>
<br />
<button type="button" onclick="removemargin()">remove margin</button>
<button type="button" onclick="removeLeftMargin()">remove leftmargin</button>
<button type="button" onclick="removeTopMargin()">remove topmargin</button>
<button type="button" onclick="addCssMargin()">add margin by adding class (dominant here)</button>

CSS

#myDiv {
    background: #EEE;
}

.myclass{
 margin : 100px 10px 15px 50px !important;
    background:red !important;
}

JavaScript

function removemargin() {
    document.getElementById("myDiv").style.margin = "0";
}

function removeLeftMargin() {
    document.getElementById("myDiv").style.marginLeft = "0";
}

function removeTopMargin() {
    document.getElementById("myDiv").style.marginTop = "0";
}

function addCssMargin() {
   var d = document.getElementById("myDiv");
    d.className = d.className + " myclass";
}