Select the node in the tree view and find the user account in the details pane. Click the button , or select from the shortcut menu of the user account to delete it. You will be asked to confirm deletion.
Deleting a user will not immediately remove it entirely. Instead, the user account is marked for deletion. This implies that the user account cannot be used anymore to log into the ITP/MDK Repository. It will also no more count against the maximum number of users in the license.
However, the account stays available as reference information. e.g., models created by this user account will still list this user account in the column 'created by', provided that the option is turned on.