you have to join as a new author using a different email and different username.
I am not sure but I think you will not be able to move your exisitng items from old account to new account because each item belongs to item author copyright. So, you have to upload new item and must have to get approved. Also you should not delete items from old account to get approve for your new account.
If you need anything to be more clear then Contact Author Support and let them know. Support Team will be happy to assist you.