Based on twitter and Reddit, I'm not the only one.
Best answer by Amy
Thank you for raising this with us. Sorry for the inconvenience caused to your experience. The lock-screen advertisements have been taken down from our servers, as they should not be appearing on lock-screen interfaces.
For the images already downloaded to your phone, you may delete as per following:
- When the image appears on the screen, slide up from the bottom edge of the screen, the operation toolbar appears. Click on 'delete' and click 'remove' in the confirmation box.