New to git and having an issue. 

**Commit ab30d85: "Github/Master" - Test 

Commit d4f6492: "Master" - Fixed error**

I need to delete and remove the ab30d85 commit and make the d4f6492 the master for github. When I try to revert the test commit I get the error below. Please help. 

On branch master
Your branch is behind 'GitHub/master' by 1 commit, and can be fast-forwarded.
 (use "git pull" to update your local branch)
nothing to commit, working tree clean