title: How to undo a merge in GitHub
body: <p>I have been working in PhpStorm on a dedicated branch, but when pushing to github, I inadvertently merged to the master branch.</p>
  
  <p>How would I undo the merge both in github and locally?  The github master is used to migrate code to various servers so I need to rollback to the previous commit prior to the merge rather than create a new commit with my changes undone.</p>