How to Hide Scolist – School Supply Lists Admin Menus

function plt_hide_scolist_school_supply_lists_menus() {
	//Hide "School supplies".
	remove_menu_page('scolistssl-sheets');
	//Hide "School supplies → All lists".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-sheets');
	//Hide "School supplies → Create a list".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-edit');
	//Hide "School supplies → Duplicate a list".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-duplicate-sheet');
	//Hide "School supplies → Import an XML list".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-import-xml');
	//Hide "School supplies → Help / Getting started".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-help');
	//Hide "School supplies → Prepare a school year".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-duplicate-year');
	//Hide "School supplies → Settings".
	remove_submenu_page('scolistssl-sheets', 'scolistssl-settings');
}

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

Where do I put this code?