In order to remove someone from the list of users who are accessing applications owned by your billing account, the billing account manager should add the user to the deny list. Denying a user ensures that the user can no longer access any application in your billing account. And, you are not charged for users who are on your deny list.
If your CSV file has a column in it that maps to the key field of the table then all you have to do is import the CSV file into QuickBase. To learn more, please see our Import Data from Outside QuickBase help topic.