How can I delete all Time Machine backups of a given folder? The delete all backups of dialog isn’t present when I right-click the folder in question.

I am trying to delete all Time Machine backups of this folder including the ones found in the local snapshots.
You must enter Time Machine by going to the menu icon and clicking on it. One of the options is to "Enter Time machine". This will bring up all your backups on the screen. When I right click on a folder I get the options shown below.





If you chose "Delete All Folders " it should do what you want.