Delete button does not work

I have this code to register and delete registration by ajax, the button Sign up It works more when I click Delete, it returns

  

Ajax Submit Failed to delete guest

But you are deleting the bank already.

Can you tell me where the error is?

<form url="cadastra_convidado.php" method="post" id="reg-form_2" autocomplete="off" style="border:none;">
    <input type="text" name="nome" id="nome" value="" placeholder="Digite o Nome do Convidado"><br>
    <input type="text" name="email" id="email" value="" placeholder="Digite o email do Convidado">
    <button class="btn btn-primary">Adicionar convidado</button>
</form>

<form url="deletar_convidado.php" method="post" id="reg-form_3" autocomplete="off" style="border:none;">
    <input type="hidden" name="deletar_convidado" id="deletar_convidado" value="<?php echo $row_convidados['id']; ?>">
    <button class="btn btn-primary" style="margin-bottom:20px;width: 100%;" type="submit">Exlcluir</button>
</form>
<div id="form-content_2"></div>  

Javascript:

$(document).ready(function () {

    $('#reg-form_2').submit(function (e) {

        e.preventDefault();

        $.ajax({
            url: 'cadastra_convidado.php',
            type: 'POST',
            data: $(this).serialize()
        })
        .done(function (data) {
            $('#form-content_2').fadeOut('slow', function () {
                $('#form-content_2').fadeIn('slow').html(data);
            });
        })
        .fail(function () {
            alert('Ajax Submit Failed ...');
        });
    });


    $(document).on('click', '#reg-form_3', function (e) {

        e.preventDefault();

        $.ajax({
            url: 'deletar_convidado.php',
            type: 'POST',
            data: $(this).serialize()
        })
        .done(function (data) {
            $('#form-content_2').fadeOut('slow', function () {
                $('#form-content_2').fadeIn('slow').html(data);
            });
        })
        .fail(function () {
            alert('Ajax Submit Failed deletar convidado ...');
        });
    });

});