I had to permanently remove a ginormous folder of seed data from the git repository history (moved it outside the project). I combined advice in several posts on removing folders/files till it worked. I'm not sure if you need all those parameters to both the tree and index filter, but it worked. *Note, be careful if you've already pushed to a sh…

remove_file_or_folder_from_git.txt

git filter-branch --prune-empty --tree-filter 'git rm -rf --cached --ignore-unmatch FOLDER_OR_FILES_TO_REMOVE' --tag-name-filter cat -- --all
git filter-branch --prune-empty --index-filter 'git rm -rf --cached --ignore-unmatch FOLDER_OR_FILES_TO_REMOVE' --tag-name-filter cat -- --all
rm -rf .git/refs/original/
git reflog expire --expire=now --all
git gc --aggressive --prune=now