The billboard, located a couple blocks south of the UCLA campus at the intersection of Westwood Boulevard and Lindbrook Drive in Westwood Village, had featured a picture of Barkley looking to the sky, taken the day he announced he was returning for his senior season last December.
The school's 2012 slogan -- "We play to finish" -- was in all caps to the left of Barkley's head, with a URL to purchase tickets placed below.
The billboard was stripped or painted over either late Monday night or early Tuesday morning and now shows nothing but a black background.
USC says it had nothing to do with it.
"USC was not involved in the decision to take any billboard down," USC spokesperson Tim Tessalone told ESPNLosAngeles.com. "We do not agree with the decision, nor were we involved in the decision to take it down."
UCLA spokesperson Nick Ammazzalorso told ESPNLosAngeles.com's Peter Yoon via text message that the school had no involvement, either, though UCLA fans had complained about the billboard on Internet message boards.
The billboard, owned by Regency Outdoor Advertising, went up last week, but it began to attract attention after the Los Angeles Times first reported on it Monday night.
A representative for Regency, who declined to be identified, refused to confirm or deny that the billboard was taken down earlier than planned. But shelf lives for such prominent advertisements are very rarely just a week, and none of the other 29 similar billboards in the area that USC purchased have been taken down or blacked out.
Asked by a reporter in a phone interview Tuesday why it was taken down, the Regency representative said it was none of the reporter's business, became irate and hung up the phone.
Regency is co-owned by two brothers, Brian and Drake Kennedy, who both attended USC. Brian Kennedy is a prominent Trojan booster; the school's smaller practice field on campus built in the late 1990's is named after him.
The company has been reported to be worth hundreds of millions of dollars, with prominent billboard spots in locations like Westwood Village and the Sunset Strip.
Barkley, considered a Heisman Trophy frontrunner, said Tuesday he was made aware of the billboard after it went up, when someone sent an image of it to him. He said he didn't have an opinion on it, adding that USC's marketing staffers were "doing their job."
Informed that it had been taken down, Barkley shrugged.
"I know they're up all over Southern California," he said. "My job is on the field, so whatever happens with that happens."
UCLA fans on online message boards congregated when the Times story was released and complained about the ad being near the school's campus, appearing to jokingly plan on a blue-paintball assault on the billboard to reclaim their territory.
"I wish some one (sic) would take the time to deface it," one fan wrote. "Just saying."
None of USC's other 29 billboards have been taken down, Tessalone said. USC's multi-platform ad campaign will continue on bus wraps and other available ad slots in Southern California and will stretch nationwide this weekend.
A similar advertisement in New York City's Times Square is set to go up on Saturday.
The top-ranked Trojans will open their season Saturday at home against Hawaii.
Pedro Moura covers USC athletics for ESPNLosAngeles.com.