There's a BOINC sever process that cleans that up. I think it's the Transitioner. Normally, that doesn't run on betas until all the results are done and they've had time to review them and determine if they find any issues. As over-rapidly as OET was shoved out into production, they're probably wanting to keep the data around longer than usual. Plus, there's also the holidays. I expect that most, if not all, of the admins are out until the 5th.