To fully reset Choices.js when reopening a Bootstrap modal, you should destroy and reinitialize the Choices instance each time the modal is shown. This ensures no cached state or UI artifacts persist:

javascript

$('#customTourModal').on('show.bs.modal', function () {
    const selectors = [
        'select[name="GSMCountryCode"]',
        'select[name="NumberOfAdult"]',
        'select[name="HowDidYouFindUsID"]'
    ];

    selectors.forEach(sel => {
        const el = this.querySelector(sel);
        if (el) {
            if (el._choicesInstance) {
                el._choicesInstance.destroy();
            }
            el._choicesInstance = new Choices(el, {
                placeholder: true,
                removeItemButton: true,
                shouldSort: false
            });
        }
    });
});

This approach ensures the Choices.js UI is reset cleanly every time the modal is reopened.