Git

Reset local repository branch to remote HEAD

git fetch origin
git reset --hard origin/master

Sync a fork with the original upstream repository via rebase

git remote add upstream https://github.com/{original_developer}/{repository}
git fetch upstream
git rebase upstream/master

# may need: git push --force

Remove latest commits from repository

To remove commits from local repository:

# Replace n with a number of the commits you want to check to remove
git rebase -i HEAD~n

To undo pushed commits to remote repository:

# Undo latest commit on remote, to undo more commits add more ^ after HEAD
git push -f origin HEAD^:master