title: How to delete table using Alembic?
body: <p>I want to delete a bunch of code from my application including several models.</p>
  
  <p>I tried deleting the file that defines the models and then did an Alemic autogenerate but the generated migration file did not appear to remove the corresponding tables.</p>
  
  <p>Any suggestions for how to do deletion in order to clear out no longer used code?</p>
  
  <p>thanks</p>