How can I keep a product URL active for SEO without listing it in my online store?

[CPG]

It is becoming problematic for 404 on discontinued products in Shopify.  Do we have the ability to leave a product URL active so that Google can still find the url, without putting it active and on the online store.  I want to be able to keep the seo on the products and the you might like these product recommendations without littering the catalogs with a lot of out of stock items.

In addition is there an easy way to only have google crawl the product pages and ignore the collection folder grouping.  So that all the urls that google finds are mystore.com/products/product_url and not mystore.com/collections/collection_name/products/product_url?