One week before 'The Late Show' signs off for good, David Letterman returned to the Ed Sullivan Theater to help Stephen Colbert say goodbye…with a little chaos.

Late-night legend David Letterman has made no secret of his contempt for CBS’ decision to cancel “The Late Show,” the program he hosted from 1993 until he retired in 2015.

“To the folks at CBS, in the words of the great Ed Murrow, good night and good luck, motherf---ers,” Letterman, 79, said to the camera, subverting the famous sign-off by CBS broadcasting icon Edward R...