Use static getCountryData method to update the data to only show localised country names.
<input id="phone" type="tel">
var countryData = window.intlTelInputGlobals.getCountryData(),
input = document.querySelector("#phone");
for (var i = 0; i < countryData.length; i++) {
var country = countryData[i];
country.name = country.name.replace(/.+\((.+)\)/,"$1");
}
window.intlTelInput(input, {
utilsScript: "../../build/js/utils.js?1549804213570" // just for formatting/placeholders etc
});