Overview

There is no built in method for completely eradicating a type/rule. But if you want to do it manually, these are the parts you will need to cover.

Simplest solution is to restart coldfusion or perform an &updateapp=1 to re-initialise the application
Otherwise set up a page to remove the type/rule from application.types/application.rules struct - there will be a key by the name of the type/rule
Remove the type/rule from application.stcoapi the same way