We had someone whom we interviewed for project on immigration who wished to withdraw the use of their interview.
We did have a signed Deed of Consent, but in that it also says the person can withdraw at any point.
This is what have done with the interview:
Kept it for reference and preserved and restricted the recording/transcription for background information use only (i.e. cannot use in publication/ thesis, etc). So it is our locked files and in secure cloud (internet) storage.