I want to discard all changes done after commit
git reset --hard <commit-hash>
Assuming that your branch is called
master both here and remotely, and that your remote is called
origin you could do:
git reset --hard <commit-hash> git push -f origin master
However, you should avoid doing this if anyone else is working with your remote repository and has pulled your changes. In that case, it would be better to revert the commits that you don't want, then pushing as normal.
Update: you've explained below that other people have pulled the changes that you've pushed, so it's better to create a new commit that reverts all of those changes. There's a nice explanation of your options for doing this in this answer from Jakub Narębski. Which one is most convenient depends on how many commits you want to revert, and which method makes most sense to you.
Since from your question it's clear that you have already used
git reset --hard to reset your
master branch, you may need to start by using
git reset --hard ORIG_HEAD to move your branch back to where it was before. (As always with
git reset --hard, make sure that
git status is clean, that you're on the right branch and that you're aware of
git reflog as a tool to recover apparently lost commits.) You should also check that
ORIG_HEAD points to the right commit, with
git show ORIG_HEAD.