How to get rid of “refs/bisect/bad” branches in Git

I have the following in my ~/.gitconfig (this is only here to help you understand what I'm looking at):

[alias]
    lg = log --graph --all --pretty=format:'%Cred%h %Cgreen(%cr)%Creset - %s %C(yellow)%d %C(bold blue)<%an>%Creset' --abbrev-commit --date=relative

When I do a git log, it shows me the full commit tree with branch names and stuff. Yesterday I initiated a git bisect and today I see there is a refs/bisect/bad branch in the output of my log.

What exactly is the refs/bisect/bad branch and how do I get rid of it?