How to Hide Joinotify Admin Menus

function plt_hide_joinotify_menus() {
	//Hide "Joinotify".
	remove_menu_page('joinotify-workflows');
	//Hide "Joinotify → All workflows".
	remove_submenu_page('joinotify-workflows', 'joinotify-workflows');
	//Hide "Joinotify → Add new workflow".
	remove_submenu_page('joinotify-workflows', 'joinotify-workflows-builder');
	//Hide "Joinotify → History".
	remove_submenu_page('joinotify-workflows', 'joinotify-history');
	//Hide "Joinotify → Processing queue".
	remove_submenu_page('joinotify-workflows', 'joinotify-queue');
	//Hide "Joinotify → Settings".
	remove_submenu_page('joinotify-workflows', 'joinotify-settings');
}

add_action('admin_menu', 'plt_hide_joinotify_menus', 100);

Where do I put this code?