Hello old man, and welcome to Seven Forums.
If there is nothing else on the drive other than the Windows Backups that you wanted to delete, then you could do a quick format of only that drive letter to get rid of them fast.
If there is, then you could just manually delete the drive letter:\computer name\Backup Set YYYY-MM-DD HHMMSS
folder on the drive that contains the backups. If you get access denied, then open each folder in Backup Set
first and approve, then try deleting them. The NOTE box at the top of the tutorial below can help give you more information about this. Backup User and System Files - Delete Backups
Hope this helps,