How do I delete all Time Machine backups of a file or folder?
After completing your first Time Machine backup, you can permanently delete backups of a file or folder using the Time Machine application. To launch the application, open ‘Finder’ and double click on ‘Time Machine’ in your ‘Applications’ folder. You can click on the timeline at the right hand side, ‘Finder’ windows in the background or navigate using the arrows at the bottom right of the ‘Finder’ window.
Once you have located the file/folder in question, click on the ‘gear’ icon in the finder window and choose “Delete all backups of XXXX”.