Note: to delete a user from your Artist PRO account, check out this article.
Delete artist/crew from an Artist Free account
The users from the an Artist Free account can only be deleted from the Agency they are linked too as Artist/Crew.
Inside the Agency environment, go to office
and to Project Management:
Click on the project where you would like to delete artist/crew. Click on 'Artist/Crew'.
The page with all the Artist/Crew will open.
You can manage the user when clicking on the sharing-icon, and delete when clicking on the bin-icon: