rollback generated controller/model in RoR
try
rails destroy scaffold XXXXXone thing that I find puzzling though is that you said "Later I discovered it would be a good idea to create the tables in the DB first..."
Well, rails creates a migration file for you when you run the generator in the first place, and this file will create your DB tables and fields when you run it using rake db:migrate
PS - here's a few good tutorials for you:
You can delete all the files Rails created -- just look at the printout on your command line, see what files rails created, and delete them.
I don't know why you would want to create all the tables in the db, but that's fine, I guess. I prefer to let rails do it. Either way, Rails won't mind. You can always add / change fields using Rails, even if you created the tables outside Rails.
Ryan Bates' Railscasts are excellent tutorials.