Data Loader delete versus hard delete
Key Takeaway
With Delete, users can restore records from the Recycle Bin. With Hard Delete, they can't, because the records never reach it.
Data Loader can delete records from Salesforce in two ways: the Delete operation and the Hard Delete operation. Delete moves the records to the Recycle Bin, where users can restore them for a limited time. Hard Delete skips the Recycle Bin, so the records are not kept there for recovery.
How Data Loader finds the records to delete
Delete and Hard Delete are separate operations in Data Loader, alongside Insert, Update and Upsert. Both read a CSV file and delete the existing records whose IDs match the IDs in the file.
Data Loader deletes records based on the IDs in the CSV file, not the object you select in the wizard.
For example, imagine you select one object in the wizard, but the ID column holds IDs of records from a different object. Data Loader deletes the records that match those IDs, even though they don't belong to the object you selected.
Because of this, check the ID column carefully before you run a Delete or Hard Delete.