How to edit or remove a user's profile picture.
You should be able to find the user's record in the live_profile table and remove the photo from there.
1) Navigate to live_profile.list
2) Search for the User whose photo you want to remove or edit.
3) Go into the record and click the Delete button under the photo.
4) Save the record.
Here is our documentation on how to update the Profile Picture as a user.