Removes all methods associated with class-specifier that pass a predicate. Class-specifier can be a class, object representing a class or symbol naming a class. The predicate should be a function of two arguments: a generic-function and a method. If dry-run? is true (and verbose? is also true), then the methods that would be removed are printed but no methods are actually removed. Returns the number of methods that are removed (or that would have been removed if dry-run? is true).