We are currently using a dev hub to perform various bits of Salesforce integration testing. Part of this testing involves changing the Chatter profile picture and creating posts/comments etc.
I suspect that every time a new profile photo is uploaded, the old one is still left in the system somewhere and not deleted, which has resulted in our dev hub using up all of its 20MB File Storage. When I check the Storage Usage tab in Settings, I can see a few MB under "Photos" (and thousands of records) for some of our users, but when you check the content library for these users the old profile files are not there.
How do I delete these records from the system?