JSFiddle - React, Tailwind, and code Playground

HTML

<select name="foo" id="myselect" multiple="true" siz="4">
        <option>1</option>
        <option>2</option>
        <option>3</option>
        <option>4</option>
        <option>5</option>
        <option>6</option>
    </select>
    <input type="checkbox" id="mycheckbox" />

JavaScript

$("#myselect option:gt(3)").remove();