Using a constituent update batch does not delete a nickname from a constituent record.
Constituent update batches are used for updating or changing existing data. If a nickname needs to be deleted it will need to be done from the constituent record.
Steps to Duplicate
1. Click Revenue tab 2. Click Batch Entry 3. Add Constituent Update Batch 4. Click Field Options 5. Add Nickname field 6. Add constituent 7. Delete the Nickname 8. Validate Batch 9. Commit Batch 10. Go to constituent profile and nickname is still listed on record