AFAIK, "destroy" only deletes the files created by "generate" (doesn't undo the database).
I have a tutorial app "tasty" http://www.tutorialspoint.com/ruby-o...-2.1/index.htm so I made a copy of it to experiment with.
It has a User model with has_many :entries in it. I did
*removed 4 files.
C:\ruby\tasty>ruby script/destroy model User
It did not delete the "child" models Entry (or Tag or Tagging beneath Entry) and entry.rb still has the belongs_to in it
class Entry < ActiveRecord::Base
# -- Tell Entry that it has a unique User associated with it.
has_many :tags, :through => :taggings