How to permanently delete skus in database

I’ve been trying to figure this out some time now and the only way I’ve came across of completely deleting deleted skus from the database is manually one by one. Does anyone else have a faster solution? Here’s the scenario, I am using woocommerce and have “permanently deleted” a bunch of products with skus in wordpress. Now these skus cannot be added again because they still exist in the database even though they’re “permanently deleted” in wordpress. I need to completely remove these deleted skus in the database so I can move onto fixing up my site to add the skus back. I cannot do this one by one manually because there are thousands of products which makes it impossible to sort out. Does anyone have a better solution on how to take care of this?

Thanks