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To create a chatroom, click "Chat", then click the "Create a Chatroom" button.
You'll need to specify a name, and also a description for the room. When you are happy with it, you should click to confirm the name, and the room will be created.
To delete your chatroom, open up the "Chatroom Settings" and on the "General" tab you will see the delete option. Please note that deletion is permanent and once a chatroom has been deleted the name can not be used again.