Yes, you can change the Depreciation Amount without deleting/re-entering your Vehicle, although that is another option.
If you sold or stopped using your Business Vehicle, enter Prior Depreciation as the same amount as your Basis.
You are correct that you get an error if Depreciation exceeds Basis, but this can happen for a vehicle has been used for many years.
More detailed info:
https://ttlc.intuit.com/replies/6242341
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