The association had announced that Slater, 39, won his record 11th ASP World Title on Wednesday when he won his second heat of the Rip Curl Pro Search San Francisco, which started at Ocean Beach on Tuesday.
However, the ASP issued a statement today saying that Slater was prematurely crowned champion because of a tie situation with surfer Owen Wright.
"This was a mistake. In the end, we're responsible for this and should be held accountable," ASP World Tour manager Renato Hickel said. "We apologize to our fans, the surfers and to Owen and Kelly."
To confirm the 2011 ASP World Title, Slater must win one more heat, either at the San Francisco competition or at the following event in Hawaii.
For Wright to remain in the running, he must win both the San Francisco and Hawaii events.
Should Slater win the title, he will be the first surfer in ASP history to win 11 World Titles.
The four-day contest in San Francisco was off on Thursday and again today, but could start again Saturday depending on weather and surf conditions in the morning. Organizers will make the call on whether to start at 7:30 a.m.
The event is being held on the northern end of Ocean Beach near stairways 18-20 and is being streamed online in a free webcast at www.live.ripcurl.com.