JSFiddle - React, Tailwind, and code Playground

HTML

<table id="table1">
    <tr><td class="cell">R1C1</td><td class="cell">R1C2</td><td class="cell">R1C3</td></tr>
    <tr><td class="cell">R2C1</td><td class="cell">R2C2</td><td class="cell">R2C3</td></tr>
    <tr><td class="cell">R3C1</td><td class="cell">R3C2</td><td class="cell">R3C3</td></tr>
    <tr><td class="cell">R4C1</td><td class="cell">R4C2</td><td class="cell">R4C3</td></tr>
    <tr><td class="cell">R5C1</td><td class="cell">R5C2</td><td class="cell last">R5C3</td></tr>
</table>
<p>Not a table</p>
<table id="table2">
    <tr><td class="cell">R1C1</td><td class="cell">R1C2</td><td class="cell">R1C3</td></tr>
    <tr><td class="cell">R2C1</td><td class="cell">R2C2</td><td class="cell">R2C3</td></tr>
    <tr><td class="cell">R3C1</td><td class="cell">R3C2</td><td class="cell">R3C3</td></tr>
    <tr><td class="cell">R4C1</td><td class="cell">R4C2</td><td class="cell">R4C3</td></tr>
    <tr><td class="cell">R5C1</td><td class="cell">R5C2</td><td class="cell last">R5C3</td></tr>
</table>
<p><input type="button" id="derClicky" onclick="removeCssClass('table2', 'last');" value="Execute removeCssClass" /></p>

CSS

.cell {padding: 0.5em;}
.last {background-color: #666;}
p {padding-top: 1em; padding-bottom: 1em;}

JavaScript

function removeCssClass(tableId, cssClass) {
    var trs = null;
    var tr = null;
    var tds = null;
    var td = null;
    var classes = [];
    var i = 0;
    
    trs = document.getElementById(tableId).getElementsByTagName('tr');
    tds = trs[trs.length - 1].getElementsByTagName('td');
    td = tds[tds.length - 1];
    classes = td.className.split(' ');
    for (i = 0; i < classes.length; i += 1) {
        if (classes[i] === cssClass) {
            classes.pop(i);
        }
    }
    td.className = classes.join(' ');
    return false;
}