If you take a backup from Central Administration -> Operations -> Perform Backup, there’s no built-in way to remove old backups. To clear up unwanted backups:
- Navigate to the backup share and take a backup of spbrtoc.xml. This file contains information about the backups.
- Within spbrtoc.xml each SPHistoryObject node corresponds to a backup. Take a note of the SPDirectoryName and SPStartTime values within each SPHistoryObject node. SPDirectoryName is the directory the backup was stored and SPStartTime is the start time of the backup.
- Delete the directories of the backups you wish to remove and delete the corresponding SPHistoryObject nodes from spbrtoc.xml.
- Navigate to Central Administration -> Operations -> Backup and restore history and the delete backups shouldn’t be visible.