The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.

https://vercel.com/docs/projects/domains/troubleshooting

You can also use v0 to narrow down the possibilities.

The project is not marked as deleted in the system, are you sure you deleted the correct project?

@khaled-7640, just checking in on your issue with the site still being up after deleting your project and domain. Have you had a chance to look into it further, or do you still need assistance? Let me know if that helps!