Thanks for reaching out and thanks for using GridOne WordPress theme. GridOne is considered one of our legacy themes and therefore is no longer updated and maintained to the most current WordPress standards.
The templates and functionality of GridOne have been incorporated into our flagship Crio Pro WordPress theme. With Crio you can be assured the theme is updated according to the latest WordPress guidelines and it will remove the outdated theme notification being produced by WooCommerce. If you decide to switch over to Crio you can keep your content design as it integrates seamlessly with Post and Page builder.
I hope this helps. Please reach back out if you have any other questions.