Today I was doing some work trying to install kalgebra with homebrew. However I came across a problem, I had manually added a formula with brew create but now I wanted to remove it (I hadn't installed it). I couldn't find how to remove it, but here is a short command I have created to do just that:
WARNING: if you have installed the formula already, please uninstall it first with brew uninstall

rm $(brew --prefix)/Library/Formula/formula_to_remove.rb

Have fun making your mac more like Linux...