How to Hide WP Media Gallery Admin Menus

function plt_hide_wp_media_gallery_menus() {
	//Hide "Galleries".
	remove_menu_page('edit.php?post_type=gallery');
	//Hide "Galleries → Galleries".
	remove_submenu_page('edit.php?post_type=gallery', 'edit.php?post_type=gallery');
	//Hide "Galleries → Add new gallery".
	remove_submenu_page('edit.php?post_type=gallery', 'post-new.php?post_type=gallery');
	//Hide "Galleries → Tags".
	remove_submenu_page('edit.php?post_type=gallery', 'edit-tags.php?taxonomy=post_tag&post_type=gallery');
	//Hide "Galleries → Albums".
	remove_submenu_page('edit.php?post_type=gallery', 'edit-tags.php?taxonomy=album&post_type=gallery');
}

add_action('admin_menu', 'plt_hide_wp_media_gallery_menus', 15);

Where do I put this code?