How to Hide the "WP G-Mappity Configuration" Admin Menu

function plt_hide_wp_gmappity_easy_google_maps_menus() {
	//Hide the "Plugins → WP G-Mappity Configuration" menu.
	remove_submenu_page('plugins.php', 'wpgmappity-api-config');
}

add_action('admin_menu', 'plt_hide_wp_gmappity_easy_google_maps_menus', 11);

Where do I put this code?