hello. My name is***** can help you with your question.
You can simply go over to the file structure and delete it from within Dreamweaver, but I find it easier to go to the folder structure where you have that site set up locally and just below the folder structure way by deleting it. Then settings from Dreamweaver so it doesn't think it still there and you're good to go. This will be easier than trying to figure out what you've deleted and haven't deleted versus what has synchronized with the server if you're using a server and all that headache. Specially right now if you're just practicing – you have nothing that you wipe out by mistake so just go delete the file structure and then delete the sites from Dreamweaver. If you have any questions though, just let me know and I'll be happy to help until your question is fully answered.