How to Hide the "Custom Fonts" Admin Menu

function plt_hide_custom_fonts_menus() {
	//Hide the "Appearance → Custom Fonts" menu.
	remove_submenu_page('themes.php', 'edit-tags.php?taxonomy=bsf_custom_fonts');
}

add_action('admin_menu', 'plt_hide_custom_fonts_menus', 102);

Where do I put this code?