Since everyone else is spamming; theres two places to do this:
1. The main page of the control panel shows "The Board is now Open", below this is an option to "CLOSE BOARD".
2. CP -> Master Settings -> Primary Settings -> Close Board?

#2 allows you to set a reason that your forum is closed

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
Do you need Forum Install or Upgrade Services?
Forums: A Gardeners Forum
UBB.threads: UBBWiki, UBB Styles, UBB.Sitemaps
Longtime Supporter & Resident Post-A-Holic
VNC Web Services: Code Modifications, Upgrades, Styling, Coding Services, Disaster Recovery, and more!