function plt_hide_premmerce_menus() {
//Hide "Premmerce".
remove_menu_page('premmerce');
//Hide "Premmerce → Premmerce".
remove_submenu_page('premmerce', 'premmerce');
//Hide "Premmerce → Contact Us".
remove_submenu_page('premmerce', 'premmerce-contact');
//Hide "Premmerce → Upgrade".
remove_submenu_page('premmerce', 'premmerce-pricing');
}
add_action('admin_menu', 'plt_hide_premmerce_menus', 1000000000);