User accounts can be made to expire by setting an expiry date in the user properties. Once a user has expired they will no longer be able to log into any site using any protocol. The user's account remains in CompleteFTP, and the account's user-name remains reserved until the account is deleted. The account may be reactivated by clearing or modifying the expiry date.
To set, user expiry date, open the Users panel, select the user and look for the user property labelled 'Expires' and either enter the full expiry date, or click the down-arrow to open a calendar control and select the date there. The expiry date may be cleared by clicking the 'x'.