Recently I got a support call from an artist who asked, “Can Column Guides be moved to set up unequal columns on a page.” The answer is yes, but you have to unlock them first. Go to the View menu > Grids & Guides > and uncheck Lock Column Guides. Click-and-drag either one of the pair of Column Guides with your Selection tool (V). Both Guides will move as a unit maintaining the Gutter width. Then relock Column Guides (View > Grids & Guides > Lock Column Guides) so they’re not moved by accident.

Tip provided by Jeff Witchel, Certified Adobe® Training Provider.