Yes, headorange. The Disable forum button is disabled, for safety reasons.
If you want to do some special work, then just make the needed sections -- or all sections -- viewable to the Admin only, while you are working.
Well, you should preferably keep one forum visible, and give some information there about what you are doing, to make sure that they don't think the forum has disappeared into thin air.
Another option is to lock some or all forums while you are working.
But none of it is needed, you can make every possible change while members are logged on, and in the middle of posting.
FoxLeonard