How to clear profile_picture & profile_picture_data in IAM using Indicium's API?

 When POSTing, the following works:

"profile_picture": {
        "FileName": "name",
        "File": "file_data"
        }

So setting a profile picture works. Now I’d like to remove/clear the profile picture of a user. I have tried the following JSON bodies in a PATCH, but none seem to work:

{"profile_picture": { "FileName": "", "File": "" }}
{"profile_picture": { "FileName": null, "File": null }}
{"profile_picture": null}
{"profile_picture": ""}
{"profile_picture": { "FileName": null }}
{"profile_picture": { "FileName": "" }}
{"profile_picture": { "File": "" }}
{"profile_picture": { "File": null }}
{"profile_picture_data": null}

How can I clear the columns ‘profile_picture’ & ‘profile_picture_data’ in the usr table in the IAM using a PATCH API call?