remove_target!

# File activerecord/lib/active_record/associations/has_one_association.rb, line 54
        def remove_target!(method)
          if method.in?([:delete, :destroy])
            target.send(method)
          else
            nullify_owner_attributes(target)

            if target.persisted? && owner.persisted? && !target.save
              set_owner_attributes(target)
              raise RecordNotSaved, "Failed to remove the existing associated #{reflection.name}. " +
                                    "The record failed to save when after its foreign key was set to nil."
            end
          end
        end