There are few different ways you can hide your products.
Put your MoreCommerce store in vacation mode
The easiest way to hide all of your products is via vacation mode, which will disable your store and every product in it. Read more about vacation mode here.
Delete your Products
You can delete products that you haven't published. (Note that when a product is imported via the bulk import tools, it is automatically published if all of the product's required information is included in the import.)
Once a product is been published, MoreCommerce preserves the data in case someone has already ordered it, so it cannot be deleted, but you can unpublished it (see below).
Unpublish your Products
You can unpublish any product via your Merchant Toolkit's product editing tools.
Unpublished products won't appear on your store pages and shoppers won't be able to buy them. You can always republish them at a later date (e.g. after editing them).
Mark your products "Out of Stock"
Change any product's inventory to 0 (edit it via your Merchant Toolkit) and it'll automatically display an "out of stock" message. You can update many products this way via the Bulk Edit tool.