Only show ACF admin page on local domain

functions.php

<?php

/**
 * Determines if string ends with a specific sub string.
 *
 * @param string $haystack The string to search in.
 * @param string $needle The sub-string to search for.
 * @return boolean
 */
function string_ends_with($haystack, $needle) {
    $length = strlen($needle);

    return $length === 0 || (substr($haystack, -$length) === $needle);
}

/**
 * Only show Custom Fields admin page on ".local" address.
 */
add_filter('acf/settings/show_admin', function () {
    return string_ends_with(
        get_bloginfo('url'),
        '.local'
    );
});