git-annex-forget man page
git-annex-forget — prune git-annex branch history
git annex forget
Causes the git-annex branch to be rewritten, throwing away historical data about past locations of files. The resulting branch will use less space, but git annex log will not be able to show where files used to be located.
When this rewritten branch is merged into other clones of the repository, git-annex will automatically perform the same rewriting to their local git-annex branches. So the forgetfulness will automatically propagate out from its starting point until all repositories running git-annex have forgotten their old history. (You may need to force git to push the branch to any git repositories not running git-annex.)
Also prune references to repositories that have been marked as dead.
Joey Hess <firstname.lastname@example.org>