Lock Cloud in Desktop App

Hello, we want to upgrade from version 2.8.9 to 3.2.xx. Is there any possibility to lock or disable the cloud? We don’t want to use this function and our employees shouldn’t be able to sign up

It is not enabled unless one explicitly signs up. Your employees can sign up no matter if they use GanttProject or not, because the web site is publicly available. If you want to restrict your employees from visiting certain web sites, you probably need to talk to your IT specialists.