Hello there, Quihgley. Looks like you've got an error the same with the screenshot below.

The message appears when you're trying to disable the Track inventory quantity on hand feature and haven't adjusted the quantity on hand of the inventory items 0 in QuickBooks Online. 

What we can do is to generate the inventory items details including the Qty on hand and other information needed and download the inventory lists. This helps you work smooth and easier. Here's how:

1. Go to Sales on the left panel.
2. In the Product and Services tab, click the Funnel icon.
3. Then, select Inventory. 
4. Click Apply.
5. If you don't see the Qty column, go to the small Gear icon. Then, tick the Qty option.
6. Then, you can export it to Excel. Click the Download icon next to the Print icon.
   

Once you have all the inventory items, you can now utilize the Inventory Qty Adjustment feature. Then, enter them manually. Note: QuickBooks will automatically show the items once you start typing the name of items. 

1. Go to the + New button.
2. Select Inventory Qty Adjustment. 
3. On the Inventory Quantity Adjustment page that appears, set the Adjustment Date.
4. Proceed to the Inventory adjustment account drop-down and select the appropriate account.
5. Enter the products in the Product field drop-down. 
6. Provide a new quantity or a change in quantity.
7. Click Save and close once you're done. 
   

Afterward, go back to the Product and Services tab and make them inactive.

1. Still, within the Product and Services tab, click the Funnel icon.
2. Then, select Inventory.
3. Under the Action column, click the drop-down arrow.
4. Select Make inactive.

You can then turn off the tracking functionality in the settings without getting an error. In you free time, you can check about managing items in QuickBooks Online. 

Let me know if you have other questions. I'll help you in any way that I can. Take care always.