how to change file from required to not required in this code?

<?php $cityIdError = (isset($errors) && $errors->has('city_id')) ? ' is-invalid' : ''; ?>
   <div id="cityBox" class="row mb-3 required">
        <label class="col-md-3 col-form-label" for="city_id"> <sup>*</sup></label>
        <div class="col-md-8">
            <select id="cityId" name="city_id" class="form-control large-data-selecter">
                <option value="0" >
                    
                </option>
            </select>
        </div>
    </div>

source https://stackoverflow.com/questions/69773044/how-to-change-file-from-required-to-not-required-in-this-code