How do I exclude a hard drive from Time Machine backup history?

Question

I've just found that a hard drive I don't need to backup has been include in Time Machine backups for a while.

Is there a way I can exclude that drive from the backup history, or all I can do is avoid it being backup in the next runs?

Answer 1

Once you’ve excluded the drive from future backups using System Preferences → Time Machine, open Time Machine on your computer, secondary-click on the disk to delete and choose ‘Delete All Backups of disk’.

http://osxdaily.com/2015/07/27/delete-old-backups-time-machine-mac/

Answer 2

Open Time Machine in System Preferences and click on the padlock icon in the lower-left corner of the pane. See image below.

Now click on the Options key in the lower right. You can select which files/folders/Volumes to exclude from your backup. See image below