How to Flatten the History of a Git Repository Safely

git-flatten-history.md

git checkout --orphan future-master
git add -A  # Add all files and commit them
git commit
git branch -D master  # Deletes the master branch
git branch -m master  # Rename the current branch to master
git push -f origin master  # Force push master branch to github
git gc --aggressive --prune=all     # remove the old files

Works well with git submodules too. From: https://stackoverflow.com/a/13102849/1253966

15 Seconds to a Cleaner Git History http://www.siliconfidential.com/articles/15-seconds-to-cleaner-git-history/

Remove git tags or branches local & remote
git tag -d v0.0.2 # deletes the tag
git push origin :v0.0.2 # deletes tag on remote server

Remove branch already merged into master
git branch -d fix4321 # deletes the branch
git push origin :fix4321 # deletes branch on remote server

How do you delete a git tag that has already been pushed? https://stackoverflow.com/questions/5480258/how-to-delete-a-git-remote-tag

git push --delete origin YOUR_TAG_NAME

Delete all local tags and get the list of remote tags:

git tag -l | xargs git tag -d
git fetch --tags

Remove all remote tags
git tag -l | xargs -n 1 git push --delete origin

Clean up local tags
git tag -l | xargs git tag -d