multi-dimensional array post from form

You can name your form elements like this:

<input name="users[1][name]" />
<input name="users[1][email]" />
<input name="users[2][name]" />
<input name="users[2][email]" />
...

You get the idea...

In jQuery documenation here: http://api.jquery.com/serialize/
Only succesful control are serialized, please see the documentation below:

Note: Only "successful controls" are serialized to the string. No submit button value is serialized since the form was not submitted using a button. For a form element's value to be included in the serialized string, the element must have a name attribute. Values from checkboxes and radio buttons (inputs of type "radio" or "checkbox") are included only if they are checked. Data from file select elements is not serialized.

So submit buttn won't serialize through jQuery.serialize() function. The work around is you can add hidden input, and it will serialized.

UPDATE:
You need to change the form submit ajax to bind the button click. and in ajax request you can add the button value manually. Below is my code that is working.

$( "#delImage" ).click(function( event ) {
    event.preventDefault();
    $form = $(this).parent('form');
    $btnid = $(this).attr('name');
    $btnval = $(this).attr('value');


    $.ajax({
        url: $form.attr('action'),
        type: $form.attr('method'),
        data: { "btnid" : $btnid, "btnval": $btnval, "form-data": $form.serialize() },
        success: function(html) {
            console.log(html);
        }
    });
});

I believe you're looking for the success in the .ajax options parameter.

$.ajax({
  ...
  success: function(d){
    alert(d);
  }
});