deleting and creating new categories in site affects seo?

dears, i am updating my site structure tree following Google taxonomy list, therefore I need to create new categories/sub-categories for our products, while linking the products to their corresponding new categories, the issue now is how to delete the old categories without hurting seo, i was thinking that maybe shopify handle the redirection automatically, or maybe i should point/redirect manually every old-category/product to new-category product manually, or simply submit new site map while doing nothing else. which practice is the best for seo in this case vs pros and cons? thanks