Matt - thanks so much for the answer...bu that's not good indeed!! So deleting the backup plan is a really bad idea? I kind of presumed we'd get asked if we wanted to keep or delete the backups (duh)!!!

If we hadn't deleted the backup plan, how would we go about removing all the backups on the storage (presumably this issue is the same for any backup storage, not just cloud-storage?)...? We can reduce the retention to one version...? But how to delete that one version...?

Also, any creative solutions as to what we do now...? Presumably, the only option would be to create a completely new set of backup plans to start on a set date...disable all the existing backup plans the day before, and then after a week or so, delete every file/folder on S3 that is dated before the start date of the new backup plans...?

Yes...