Yes and no. If you reduce the data set by unchecking folders you may be backing up, the backup plan will no longer be managing that folder and it will leave the backups for that folder in backup storage. You would need to then manually delete the folder from the Storage tab in the UI. If you change something like the retention to keep fewer copies of backups, the backup plan still may not run if files need to be backed up - the backup process runs before the retention is applied and if the storage limit is still exceeded, the backup plan will fail. Or you can upgrade the license to Ultimate (I assume this is a Windows Server).

Let me know what you decide and I'll provide additional details if needed.

Thanks. I'm setting the retention policy now in BW to purge old files and also removed some unnecessary ones that were there.