We have a customer in our project who has a double account, I guess one is made with an e-mail and one true our portal. When I open the user's profile I get an error it does not exist. See the added file.
When I open our project settings a go to users, there is only one account available, the one that's correct. I deleted the double account, but when a new item is created I can still select the double account.
Is there a way I can delete or disable a users account? 
I look forward to hearing from U.