If it's a road tire, I'd just leave it. A recommended rotation for a road tire tread is just a bunch of hogwash. In practice it makes zero difference. In fact the minimal tread pattern on a road tire is just there to give the consumer the impression that they're going to get better traction and in reality it makes no differnence whatsoever. A smooth tire gets the best traction on pavement.
And that's not just me spewing ****. That's according to Jobst Brandt who is probably the foremost expert on the topic. He's a mechanical engineer that worked for Porsche and then went on to work at Avocet Bicycle Products where he designed machines used for testing the traction and breakaway characteristics of bicycle tires. He also authored the book "The Bicycle Wheel".