Is there a way to toggle off the sidebar on JU? If there is, I can't find it. If not, that's my suggestion box item for today - it's redundant, not to mention ugly & inconsistent with the forum redesign.
It really wasn't an April Fool's thing.
There's not a way to disable the sidebar.
Then may I humbly request the design team redesign its appearance to blend better. Just a suggestion, since you've gone to all that trouble to do the forum makeover.
There are many great features available to you once you register, including: