How to Free Up Repository Space?

Our repository is getting full.  I need to reclaim space immediately. 

I have shortened retention policy for a number of jobs, but it seems like it takes forever for these jobs to roll off. 

We also had one machine that had multiple base images due to dirty shutdowns.  Three days ago, I deleted the oldest, which was 3 TB.  We have seen zero (0) space reclamation. 

How do I free up space on this thing?

I assume that if I completely remove a machine from protection and delete all recovery points, that *might* do the trick (although at this point I'm not even sure that would do it).  But obviously that's not a good solution if it's still a production machine.

Has anyone ever used the secret "hard delete" option?  What does that do?

Thanks