Hi there, @ingailzepeterson. In QuickBooks Online (QBO), you can only make the vehicle inactive to protect your historical tax records. This ensures your past mileage deductions remain accurate while removing the vehicle from your active lists.
To complete this process, navigate to All apps > Expenses & Bills > Mileage. Click on the Add trip dropdown and choose Manage vehicles. Select the vehicle in question and click vehicle no longer in use to make it inactive. 
After saving, verify the status in the Manage vehicles menu. The vehicle will remain visible but listed as inactive. You can select it again to confirm the inactive status or reactivate it if needed.
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