Once a domain URL & email is registered with TinyTake the same cannot be modified since all your captures made via TinyTake are tied to the same.
As an alternative you can send a request to support@tinytake.com to delete the existing TinyTake account and then create a new one.
Warning: Please note that doing this will permanently delete all your captures or files on TinyTake and can not retrieved back, the data can not be transferred to any other account as well.