everything is incremental, so it's not possible to delete individual incremental restore points. You can update the retention policy if needed and try to manually age out the older backups once the next backup completes and can force a full on the next execution if you want. But other than that there's no way to delete these types of incremental backups, especially if you're using the new archive backup format on file folder backups, or using the legacy format for image or VM style backups.
Thanks for the speedy response, David. Some follow-up questions.
FYI I am using the new file formats - not legacy.
1) Will the retention policy change date be related to the actual files or the full/inc backup date?
e.g. scenario
Retention policy is set to keep files for 4 months.
Backup is set to run daily at 3am.
For the month of July, there are full + inc backups from 07/01/21 - 07/31/21, and I can see the full gen set in the backup storage tab.
In August run, to delete all the files from July, I would then set the retention policy to, say, 30 days. But that would then delete all the files backed up in July, instead of specific ones I no longer need.
2) Isn't there a way to have a backup delete from remote storage files that were already deleted locally? Sort of a sync?