This document covers how to add or remove an existing production from a StoreFront page.
First navigate to the pages tab of the StoreFront.
Click on the edit icon for that page that you want to adjust items on as shown below.
Now click on the Items tab as shown below.
To add an item simply enter the item id into the search field. As you type values into the field results will appear.
Click on the result row to assign the item. You can click it again to delete the assignment or click the red trash can icon next to the assignment as shown below.
Make sure you click on Save Page when you are finished to make sure changes take effect.