Example of how to remove the PDF icon and use a custom URL for the Receipt button.

thank-you-page-overview.template.php

<?php
/** @var EE_Transaction $transaction */
/** @var boolean $revisit */
/** @var string $order_conf_desc */

do_action('AHEE__thank_you_page_overview_template__top', $transaction);

?>

<div id="espresso-thank-you-page-overview-dv" class="width-100">

    <?php if (! $revisit) : ?>
        <div class="ee-attention">
            <div class="extra-padding-sides">
                <?php echo apply_filters(
                    'FHEE__thank_you_page_overview_template__order_conf_desc',
                    sprintf(
                        $order_conf_desc,
                        '<h3 class="">',
                        '</h3>',
                        '<br />'
                    )
                );
                $my_custom_url = 'https://example.com';
                if (! empty($my_custom_url)) : ?>
                    <br/>
                    <div class="jst-rght">
                        <a class="ee-button ee-roundish indented-text big-text"
                           href="<?php echo $my_custom_url; ?>">
                            <?php
                            echo apply_filters(
                                'FHEE__thank_you_page_overview_template__order_conf_button_text',
                                __('View Full Order Confirmation Receipt', 'event_espresso')
                            );
                            ?></a>
                    </div>
                <?php endif; ?>
            </div>
        </div>
        <br/>
    <?php endif; ?>
    <br/>

    <?php do_action('AHEE__thank_you_page_overview_template__content', $transaction); ?>

</div>
<!-- end of espresso-thank-you-page-overview-dv -->

<?php do_action('AHEE__thank_you_page_overview_template__bottom', $transaction); ?>