It's good to see you here in the Community, @TCDK.

When inactivating an item in QuickBooks Online, the information will still show up on the previous transaction created. However, the item will have the word deleted beside it, which indicates that it has been inactivated already. Please see the sample screenshot attached for reference: 

The item will longer be used on the future transactions unless you make it active again. To give you more details about modifying the products and services in QuickBooks Online, please see this link: Remove or merge a product or service.

I'm also adding here an article about adjusting inventory quantities in QBO in case you need to make adjustments with the items.

I'll be around to help you if there's anything else you need. You can always find me here. Have a good one!