How to Hide the "Block Patterns" Admin Menu

function plt_hide_coblocks_menus() {
	//Hide the "Appearance → Block Patterns" menu.
	remove_submenu_page('themes.php', 'edit.php?post_type=coblocks_pattern');
}

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

Where do I put this code?