function plt_hide_mailgun_menus() {
//Hide the "Settings → Mailgun" menu.
remove_submenu_page('options-general.php', 'mailgun');
//Hide the "Settings → Mailgun Lists" menu.
remove_submenu_page('options-general.php', 'mailgun-lists');
}
add_action('admin_menu', 'plt_hide_mailgun_menus', 11);