Uber Technologies Inc. has stopped its self-driving pilot program in San Francisco after state regulators revoked the cars’ registrations late Wednesday.

The California Department of Motor Vehicles had demanded that Uber obtain a permit for its driverless cars, as 20 other autonomous-car companies have, since the program started last week. Uber had refused, saying that because their cars required someone in the driver’s seat to monitor the vehicle, they weren’t technically self-driving.