When you archive a product in Sumtracker it is removed from the product list. The product is still accessible in the "archived products" list. To access the archived products follow the below steps:

Go to products list and click on "more" menu option. Then select see archived products menu option.

From the archived products list page you can unarchive or delete the products.

Go to the archived products list page as explained above.

Now select the products which you want to unarchive. Then you have to click on "bulk actions" button and then click on "undo archive products"