Enabling the Track Inventory setting will decrement the quantity on hand value based on the quantities ordered on the Types of orders you set up to do so. 
The section of the Inventory Setting must show the types of orders that will trigger the deduction of the inventory once the order is submitted. Order types are actually named in the App Settings initially, once set then this section triggers which of those types will remove inventory. Those types of orders that will reduce inventory need to be placed here using the exact name, separated by a comma with no space.
Enabling the Inventory Items will hide products based on the threshold established by the WebManager and set in the Low Inventory ThreshHold section
Setting a Low Inventory Threshold will hide the products when they get to this number & below. Once the inventory of products is replenished the product will show back up.
Place the number of inventory that establishes the products to not be shown on the app and not ordered here - Save!
Next, we'll learn how to manage the Landing Page