To edit or delete the mapping of parent records from the Source to the Destination org, follow these steps:
- Navigate to the "Mass File Migrate" app.
- Go to the "About Mass File Migrate" tab.
- Locate the "Map parent records from Source to Destination org" section and click on the "Click Here to configure the parent record mapping from Source to Destination org" link.
- A configuration window will open.
- On the right-hand side, you can see two icons for editing and deleting.
- To edit the mapping, click on the "Edit" icon.

- Make the necessary updates and click on the "Save" button

- To delete the mapping, click on the "Delete" icon.

- Upon successful deletion, you will receive a success message on the screen.

PS: View Mass File Migrate Salesforce file migration app on Salesforce AppExchange:
https://appexchange.salesforce.com/appxListingDetail?listingId=e9874a66-2001-4e3d-8a29-3a2ed7f584c4