Question:

How to Data Load records and assign to Inactive users? 

Answer:

Prior to 2017, Salesforce needed to be contacted to make necessary changes.  The Update Records with Inactive Owners setting is used to update the owner and sharing-based fields on records with inactive owners.

To make the change, follow these steps:

1. Navigate to: Setup.
2. Type: User Interface in the Quick Find box.  Press Enter.
3. Select User Interface under Customize. 
4. Enable the permission. 

Note: If using a System Administrator Profile, it is not possible to edit standard profiles to assign the required profile permission. Assign permissions through the use of a Permission Set.

Related Documentation:

SFDC Help Documentation: 

• Set Audit Fields and Update Records with Inactive Owners
• Enabling Create Audit Fields for Professional Edition

Thank you