Add more fieldset with remove option custom module

I'm developing custom module and there's one fieldset that can be added multiple times and can be removed any particular entry also. Can anyone please suggest to achieve this? Here is my code:

function hook_form($form,&$form_state){
$form_state['storage']['emails'] =
isset($form_state['storage']['emails']) ? $form_state['storage']['emails'] : 0;

$form['emails'] = array(
    '#type' => 'container',
    '#tree' => TRUE,
    '#prefix' => '<div id="emails">',
    '#suffix' => '</div>',

);
if(empty($form_state['storage']['emails'])) {
    $form_state['storage']['emails'] = 0;
}
for ($j = 0; $j <= $form_state['storage']['emails']; $j++) {
    $form['emails'][$j]['candidate_email'] = array(
        '#title' => 'Email',
        '#type' => 'textfield',
        '#size' => '30',
        '#required' => FALSE,
    );
}
$form['emails']['add_email'] = array(
    '#type' => 'button',
    '#value' => t('Add Email'),
    '#href' => '',
    '#ajax' => array(
        'callback' => 'hook_ajax_add_emails',
        'wrapper' => 'emails',
    ),
);
$form_state['storage']['emails']++;

$form['submit'] = array(
    '#type' => 'submit',
    '#value' => 'Submit',        
);
return $form;
}

function hook_ajax_add_emails($form, $form_state) {
    return $form['emails'];    
}