Hi --
in your Rails app path to drop all your migration to the start point: rake db:migrate VERSION=0 to bring up the db: rake db:migrate
To roll the database back to a previous migration version: rake db:migrate VERSION=X
Deleting the tables and remigrating shouldn't cause any problems (as long as you don't care about the data).
The schema table keeps track of migrations, so by deleting it and everything else you should be at square one.