How to update HTML content without using redirect after a REST request?

I have been told issuing a redirect('/') for API requests is not RESTful. I have been doing it like so:

app.delete('/items/:id', urlencodedParser, (req, res) => {
    let index = parseInt(req.params.id);
    items.splice(index, 1);

    res.redirect('/');
});

I now know this is wrong. But then what do I need to do to update the content on the HTML web page without refreshing the page manually?

Read more here: https://stackoverflow.com/questions/65835547/how-to-update-html-content-without-using-redirect-after-a-rest-request