How to permanently delete Attributes in WooCommerce for WP?

I’m using Woocommerce for WP to set up my new eCommerce website. I need to start from scratch with our Attributes in order to use a csv importer. WP is remembering all the previous Attributes that were uploaded even after deleting and optimizing the database. Can you please tell me how to permanently delete these attributes so I can finish up adding our 6,000 product variations. I certainly do not want multiple duplications to a occur in the process.

I’m not sure if this would involve the MYSQL or PHP, which I am not familiar with and have trepidation in trying. I don’t want to mess anything up that is now working. Of course, I have a deadline I’m trying to meet too.

Many thanks!