JSFiddle - React, Tailwind, and code Playground

HTML

<form>
    <ul>    
        <li><input type="checkbox" />item one</li>
        <li><input type="checkbox" />item two</li>
        <li><input type="checkbox" />item three</li>
        <li><input type="checkbox" />item four</li>
        <li><input type="checkbox" />item five</li>
        <li><input type="checkbox" />item six</li>
        <li><input type="checkbox" />item seven</li>
        <li><input type="checkbox" />item eight</li>
        <li><input type="checkbox" />item nine</li>
        <li><input type="checkbox" />item ten</li>
    </ul>
    <input type="submit" value="Delete (0)" />
</form>

JavaScript

var getChecked = function($form) {
    return $form.find('input[type="checkbox"]:checked');
};

$form = $('form').on('submit', function(e) {
    e.preventDefault();
    getChecked($form).each(function() {
        $(this).parent().remove();
    });
});

$form.find('input[type="checkbox"]').on('change', function(e) {
    $form.find('input[type="submit"]').val('Delete (' + getChecked($form).length + ')');
});