I have forked a repository, then I made some changes and it looks like I\'ve messed up everything.
I wish to start it again from scratch, using the current upstrea
Following @VonC great answer. Your GitHub company policy might not allow 'force push' on master.
remote: error: GH003: Sorry, force-pushing to master is not allowed.
If you get an error message like this one please try the following steps.
To effectively reset your fork you need to follow these steps :
git checkout master
git reset --hard upstream/master
git checkout -b tmp_master
git push origin
Open your fork on GitHub, in "Settings -> Branches -> Default branch" choose 'new_master' as the new default branch. Now you can force push on the 'master' branch :
git checkout master
git push --force origin
Then you must set back 'master' as the default branch in the GitHub settings. To delete 'tmp_master' :
git push origin --delete tmp_master
git branch -D tmp_master
Other answers warning about lossing your change still apply, be carreful.