I know that I can go back in history to earlier commits using git reset --hard <commit>. However, this only lets me roll back to the first commit (not before the first commit).
I want to do this, since I created a Git repository and committed a lot of wrong files and directories. Simply deleting the repository and starting over is not an option here, since repositories are created by an admin.
How can I reset my Git repository to the state before the first commit?
You can do whatever changes you want, and amend to the last commit:
# do changes
git commit --amend
# enter a new commit message if you wish
If you want to merge two commits, you can use git rebase -i --root which allows you to handle the very first commit with the next ones.
As an alternative to amending the first commit, you can also create a fully new branch using git checkout --orphan and then reset master to that one:
git checkout --orphan new_master
# add files
git commit -m "new initial commit"
git checkout master
git reset --hard new_master
git branch -D new_master
git checkout --orphan temp # Start a new history with a dummy initial branch
# Prepare your first commit...
git commit # As usual, this will actually create the temp branch
git checkout -B master # Bring master onto this new commit
git push --force origin master # Update the remote, dropping the old history
git branch -d temp # Delete the temporary branch
