A far easier workaround (especially if it’s been a while) is to go to the list of branches (https://github.com/your-org/your-repo/branches) search for your branch, recreate it, cancel the build on CircleCI, and then delete the branch again.
A far easier workaround (especially if it’s been a while) is to go to the list of branches (https://github.com/your-org/your-repo/branches) search for your branch, recreate it, cancel the build on CircleCI, and then delete the branch again.