Backup drive full

change retention policy (at client bu) of OFFSITE backups to 1 month or less. Then it will delete old copies.

if you can’t do the above, you can do it manually. looks like you have to do it on the client computer
With version 8 if to reclaim free space on your backup location, you should follow these two steps:

1. Use the “Delete Backup Versions” tool – https://help.altaro.com/hc/en-us/articles/4416905870865-
2. After that, please use the RDF Optimization tool – https://help.altaro.com/hc/en-us/articles/4416899892369

The first tool (Delete Backup Versions) should be a lot quicker since it only marks the blocks as “free”.
The second tool (RDF Optimization) is more time-consuming because it converts those “free” blocks as free space.
Important: please note that the (RDF Optimization) takes a long time to finish during which you will not be able to take any backups and there is a default timeout in place that will basically fail the job if it doesn’t finish in 48 hours. So if possible, perhaps the best time to start it would be before the weekend.