JavaScript - quitar required a campo de texto segun opcion

<input style="width:80%; height:30px; font-size:14px;" name="txt9" type="text"  onkeyup = "validar(this.form)" id="txt9" required>

<input type="radio" name="interesado" value="si" id="si" checked> Sí

    <input type="radio" name="interesado" value="no" id="no">

<form>

<input type="checkbox" id="checkField"/><label>Required field</label><br/>

<input type="text" id="textField" placeholder="Input text here"/><br/>

<input type="submit" value="Submit"/>

</form>

<script type="text/javascript">

  const textElement = document.getElementById("textField");

  const checkElement = document.getElementById("checkField");

  checkElement.addEventListener("click",(e)=> {

  	if (checkElement.checked)

    	textElement.required = true;

    else

    	textElement.required = false;

  });

</script>