Bitrix убрать $_GET['success'] из url и скрыть popup с фразой об успехе.

component_epilog.php

<? if (!defined("B_PROLOG_INCLUDED") || B_PROLOG_INCLUDED !== true) die();
// include_once('./phpHtmlWriter.php');
global $APPLICATION;

if ($_GET['success'] != null) {
    echo '
        <script>
            $(function() {
                $(".callback-form_success").find(".mf-ok-text").text("'.$arResult["OK_MESSAGE"]. '");
                $(".callback-form_success").css("display", "flex").show();
                $("html").css("cursor", "pointer");
                $(window).on("click", function() {
                    $(".callback-form_success").hide();
                    var url = window.location.href;
                    url = url.split("?")[0];
                    console.log(url);
                    window.history.pushState({}, document.title, url);
                });
            });
        </script>
    ';
}

footer.php

</footer>
<!-- Успех отправки формы-->
<div class="callback-form_success">
    <div class="ok-text"></div>
</div>

style.css

.callback-form_success>.ok-text {
    color: #ff8d13;
}
.callback-form_success {
    box-shadow: 0 0 25px 15px rgba(0,0,0,.5);
    position: fixed;
    top: 30%;
    z-index: 99;
    height: 240px;
    max-width: 670px;
    margin: auto;
    left: 50%;
    transform: translate(-50%);
    width: 100%;
    display: none;
    justify-content: center;
    align-items: center;
}