How can one sincerely repent of publishing offensive images on the internet while these images remain available, and will Allah forgive this sin after sincere repentance?

If a servant repents from a detestable act, he must strive to remove all its traces. This involves erasing what he wrote and the images he posted on the websites where the evil was disseminated, and convincing the officials to do so. If he is unable to do that, then he must be sincere and truthful in his repentance. He is also advised to be active in inviting people to Allah through the internet and spreading goodness.