Deleting subdirectory from all backups

[Yves Bellefeuille]

I have a directory /foo and a subdirectory /foo/bar.

In the past, I backed up the entire directory /foo, so also the
subdirectory /foo/bar.

Now I've decided that I want to delete all backups for the
subdirectory /foo/bar, while keeping everything else.

Is this possible? Can I simply delete the subdirectory in the backups?

Thanks.

-- 
Yves Bellefeuille
<yan@storm.ca>