How to remove Category and Products

I recently uploaded an affiliate feed and when I did it didn't create the categories the way I wanted - I can fix that but how can I remove all the data in my database so I can restart my process cleanly? I don't need any of the data in my database as well. I'm tried to hit the backend database and empty it but that didn't work. I am now deleting each category one by one and there are many of them.

Any work arounds?

I know how to delete all of the products, but not sure on all the categories.
To delete the products, you:

1. Go to Tools/Easy populate
2. Create COMPLETE tab-delimited .txt file.
3. Open in Microsoft Excel or similar
4. In the Product_Status column make the number 9 rather than 1

And then upload the txt file into the database and viola! You have no more products in your store :)
Hope that helps a little.

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