I have 2 "forums/sections" in my Forum called "General Chat & Discussion" and "Off Topic" and I want to move all of the "topics/posts" from the Off Topic section into General Discussion so I can delete the "Off Topic" section.
Is there a way of moving everything at once or do I have to do it 1 at a time with "quick mod tools" ?
Here is my URL and a screen shot.
http://www.detectingwestaustraliangold.com/

Click the on the forum, then it will move you to an option where you'll ask if you'd like to transfer its content to what forum. Click the drop down field then find the forum you want the topics to move then click Delete button.

When you say X, do I assume it is done in the Admin Panel ?

Yep.
It is on the ACP > General > Forum > Categories and forums

Thanks for your help E-Mark, it's done.