I had a flat tire. How can I reset the "warning"?

Look in the owners manual.

I have looked at all the relevant sections. Nothing there

I had to do a tpms obd relearn to get rid of the warning. I used a bartech tool that could service the tpms system.

I tried ODBII and didn't find a fault code. It resolved itself when I had another warning for low fuel, and without turning off the car (not SOP), I filled the tank. The flat tire warning disappeared; I'm not sure if it's correlation or causation, but it happened to work. I hope that helps.

This recently occurred on my wifes Q50. It reset on its own after so drove it for a week or so. Not the fastest reset, but no trip to the dealer needed either.

I had a "run flat" tire repaired a few days ago and took it back to Discount Tire when the computer did not clear. They have a hand-held portable electronic device that plugged in under the dashboard on the driver's side, and it cleared the issue in less than 5 minutes.