How to Hide Upsellar Admin Menus

function plt_hide_upsellar_menus() {
	//Hide "Upsellar".
	remove_menu_page('upsellar-dashboard');
	//Hide "Upsellar → Dashboard".
	remove_submenu_page('upsellar-dashboard', 'upsellar-dashboard');
	//Hide "Upsellar → Appearance".
	remove_submenu_page('upsellar-dashboard', 'upsellar-appearance');
	//Hide "Upsellar → Settings".
	remove_submenu_page('upsellar-dashboard', 'upsellar-settings');
}

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

Where do I put this code?