How do I make a product show out of stock regardless of inventory levels?

Created by Ezra Weinstein, Modified on Tue, 23 Aug 2022 at 05:35 PM by Ethan Harris

Go to System > Custom Fields > Custom Field Builder.
Set the Custom Field Type to “Products”,
Type in the Form Label, “Force out of stock regardless of inventory levels”,
Set the Field Type to “Checkbox”.
Lastly, check the box that says Internal Use Only
Go to the product in Product Maintenance and, in the Data tab, check the box for this new custom field.
This will cause the system to see this product as out of stock regardless of the inventory levels.