If I understand well, I will access my storage using file explorer, I will delete the older backup files and vembu will automatically recognize the free space created. No other action needed.

Yes, you are right. After deleting unwanted backup data from the storage location through file explorer, Vembu application will take some time to recognize the storage space details. New backups will be allowed once the storage space details are captured by the Vembu application. We are planning to include retention policy in Free Edition in our upcoming release version 3.9 which expected to be released in mid of Oct 2017. Once this retention feature is included users can set the retention policy for their backup job to cleanup older backup data automatically.

Thank you very mach for your reply.