I have committed wrong files to my branch and pushed it to origin. I have seen the article at How to undo last commit(s) in Git? that deals with undoing a local commit, but my problem is that I have pushed the commit to origin. How to undo this?
Since you've already pushed to origin, your change has been published for others to see and pull from. Because of this, you probably do not want to rewrite the history. So the best command to use is git revert.
This creates a new commit that reverses the changes you made. Push the new commit and origin will be fixed.
Here is an SO answer that gives more details on this.