You could moderate and approve any forum topic that is newly created before it is published on your Freshdesk portal. To set up Forum Moderation, kindly navigate to Admin > Channels > Portals > Settings > Moderate Forums and select the option "Moderate all Topics and Replies".
To approve a forum go to the Dashboard and scroll down. You will find an option of "Forum Moderation" on the right pane. Forum topics and replies that are awaiting moderation would be listed there and you could approve the topics to be published.