Don Lemon was conspicuously absent from “CNN This Morning” on Friday just 24 hours after he put his foot in his mouth with a sexist comment about 51-year-old Nikki Haley being “not in her prime” — prompting co-host Poppy Harlow to walk off the set. “CNN This Morning” co-host Don Lemon was conspicuously absent from the set on Friday. “The people I am closest to in this organization are women,” Lemon insisted, according to a transcript of his apology obtained by The Post. Lemon had “the day off” just 24 hours after he went on a sexist rant that enraged co-host Poppy Harlow. But a source close to the veteran anchor quipped: “As a woman in her prime, Poppy Harlow does use the bathroom, including on Thursday mornings.”Additional reporting by Alexandra Steigrad