I'm actually working on another option where the last person that has a task on the form process is forced to click into a field where they "acknowledge" that they have deleted the upload.  

The form allows for the applicants to type in their banking info OR upload a blank check so the final copy of the process that saves into LF is now also hiding the table that holds the banking details and has a new field that just declare that the banking details have been removed to protect the privacy of the applicant's information.

Neither options are neat and tidy, but ... they will work.

Also, Samuel, there is a third option that I'm working on, but I'm getting confused about the best redact option.  Can you tell me which option will hide the details from all our staff except Workflow?

You would use the Protected option you have selected there. See the "Annotation Protection" section of the Apply Text Annotation documentation for descriptions of all the levels. You would also want to set the Entry Access Rights on the document to add an explicit Deny for "See through redactions" on the Everyone group.

If you really don't want anyone to see the doc, use the Delete Entry activity with the "Purge entry after deleting" option checked. This irreversibly deletes the entry so it can't even be recovered from the Recycle Bin.