How do I delete all revision of a file except for the most recent version?
Hi. This is not somthing that the GIT system was desined to do. As you would need to rewrite the history of your repo.
You will need to look up the git filter-branch command of the BFG app. This article: https://help.github.com/articles/removing-files-from-a-repository-s-history/ have a lot of informatin on the subject.