It seems every ArchivePurge job takes up >900MB disk space, so it ends up consuming over 5GB with jobs 1-48. How to safely free up the disk space and limit the space usage?
Purge the jobs ;-). Seriously, you should first delete all completed ArchivePurge jobs using the RME Job Browser, or the Archive Mgmt Job Browser to quickly free up space. Moving forward, check to make sure all of your debugging is disabled under RME > Admin > System Preferences > Loglevel Settings (click the Default button to be sure).
Finally, add a schedule to purge archive purge jobs under RME > Admin > System Preferences > Job Purge.