How to Perform Mass Deletes using Salesforce Data Loader?
Step 2: And after, exporting the records you wish to delete, this time using only the record ID as the desired criterion.
Step 3: Now, launch the Data Loader, and use the wizard of delete or hard delete wizard. In the wizard map only the ID column. For more info see Insert, Update, or Delete Data Using Data Loader.
Step 4: At last, after completing the wizard operation, review your success and error log files. See Review Data Loader Output Files.