Delete a github branch [duplicate]

Question

Possible Duplicate:
How do I delete a Git branch both locally and in Github?

First of all, I read how to remove a branch, but for some reason is not working on my project: https://github.com/ralcr/sdk.ralcr

When you first enter here you see some files 10 months old in a gh-pages branch. I have no idea how this branch was created and why it's displayed first, but I want to remove it and this is not working

Balutas-MacBook-Pro:sdk.ralcr Cristi$ git push origin --delete gh-pages
fatal: 'origin' does not appear to be a git repository
fatal: The remote end hung up unexpectedly

I want only the master branch.

Answer 1

I found the solution here: https://github.com/matthew-brett/pydagogue/blob/master/gh_delete_master.rst I couldn't delete the branch because was the default branch. To change it go to Admin and there's a drop down for that.