The backup tool can use the --retainPreviousFullBackupCount or --retainPreviousFullBackupAge arguments to identify which previous backups to preserve.
Any other backups in that directory are removed. A new backup is always preserved. However, older backups in the same directory are eligible to be removed.
If you include the --retainPreviousFullBackupCount argument, that number of the most recent previous full backups are preserved and any other previous full backups are removed. A value of zero can be specified for the --retainPreviousFullBackupCount argument so that only the most recent backup is preserved and all previous backups are removed.
If you include the --retainPreviousFullBackupAge argument, its value must be a duration represented as an integer followed by a time unit. Any full backups created longer ago than that duration are eligible to be removed.
If you include both the --retainPreviousFullBackupCount and --retainPreviousFullBackupAge arguments, then only backups that don't satisfy either condition are deleted.
The remove-backup tool also supports the --retainFullBackupCount and --retainFullBackupAge arguments to delete any backups outside the provided retention criteria.