How to Hide GrandWP Gallery Admin Menus

function plt_hide_photo_gallery_image_menus() {
	//Hide "GrandWP Gallery".
	remove_menu_page('gdgallery');
	//Hide "GrandWP Gallery → Galleries".
	remove_submenu_page('gdgallery', 'gdgallery');
	//Hide "GrandWP Gallery → Views / Styles (Pro)".
	remove_submenu_page('gdgallery', 'gdgallery_styles');
	//Hide "GrandWP Gallery → Settings".
	remove_submenu_page('gdgallery', 'gdgallery_settings');
	//Hide "GrandWP Gallery → Featured plugins".
	remove_submenu_page('gdgallery', 'gdgallery_featured_plugins');
}

add_action('admin_menu', 'plt_hide_photo_gallery_image_menus', 11);
Where do I put this code?