How to Hide Streamweasels Twitch Integration - Rail Add-on Admin Menus

function plt_hide_ttv_easy_embed_menus() {
	//Hide the "Plugins → Install Plugins" menu.
	remove_submenu_page('plugins.php', 'tgmpa-install-plugins');
	//Hide the "Settings → [StreamWeasels] Twitch Rail" menu.
	remove_submenu_page('options-general.php', 'twitch-tv-rail');
}

add_action('admin_menu', 'plt_hide_ttv_easy_embed_menus', 21);

Where do I put this code?