PROCEED AT YOUR OWN RISK!

I TAKE ABSOLUTELY NO RESPONSIBILITY IF YOU ATTEMPT TO FOLLOW THESE INSTRUCTIONS AND DESTROY YOUR EXCHANGE SERVER IN THE PROCESS!

If you have Exchange 2007, please follow these instructions.

If you are running Exchange 2003 with SP2, then it is almost impossible to remove Public Folders that haven't been replicated onto other servers. There is a built in check that will warn you to Move All Replicas, and will double-check that this has actually happened before it will let you delete a public folder store. This is a good idea, since in versions before SP2 you were able to delete them without blinking... not good if you had data in them. So what if you're running SP2 and you only have one server... and you are sure you want to delete your public folder store? Well thanks to a Microsoft employee called Bill Long, I now know how to do it, and this I share with you now.

Run ADSI Edit.
Drill down to...

Configuration
+ CN=Configuration
 + CN=Services
  + CN=Microsoft Exchange
   + CN=YOUR ORGANISATION
    + CN=Administrative Groups
     + CN=First Administrative Group
      + CN=Servers
       + CN=SERVER NAME
        + CN=InformationStore

You should be able to see your Storage Groups in this container. You can select it on the left, and see the stores within it in the righthand pane.

If you need to remove a store, delete it then stop/start the Microsoft Exchange Information Store service to be sure that it's removed, and you can now delete the files related to the store.

Again, I say... PROCEED AT YOUR OWN RISK!