We make a .env file and accidentally push it to github.
In order to remove the .env file, we first have to add it to our .gitignore file - but that's not enough, because the .env file will still be on the branch on github.
So we can remove all of our files from our git cache with:
git rm -r --cached .
and then add back all the files we want with:
git add -A
(that will exclude the .env file this time - because of the .gitignore file).
Then we can commit that change (which is effectively the same as removing the .env file), and push it, which will remove the .env file from the mater branch.
IMPORTANT! If you have secrets in a file that you remove in this way, you should still consider those secrets compromised, because anyone could have pulled them already - and they are also still in the git history.