How to Hide Gutenslider — The last WordPress slider you will ever need. Admin Menus

function plt_hide_gutenslider_menus() {
	//Hide "Gutenslider".
	remove_menu_page('settings_page_gutenslider');
	//Hide "Gutenslider → Gutenslider".
	remove_submenu_page('settings_page_gutenslider', 'settings_page_gutenslider');
	//Hide "Gutenslider → Contact Us".
	remove_submenu_page('settings_page_gutenslider', 'settings_page_gutenslider-contact');
	//Hide "Gutenslider → Support Forum".
	remove_submenu_page('settings_page_gutenslider', 'settings_page_gutenslider-wp-support-forum');
	//Hide "Gutenslider → Upgrade".
	remove_submenu_page('settings_page_gutenslider', 'settings_page_gutenslider-pricing');
}

add_action('admin_menu', 'plt_hide_gutenslider_menus', 1000000000);

Where do I put this code?