What is the procedure for deleting a project in drupal.org?
If your project contains code usually it is not deleted. In that case, you can select as Project classification Unsupported and as a Development status Obsolete.

You can always create a post in the Drupal.org webmasters issue queue explaining your situation and requesting the project deletion.

But I can tell you that if you have people using your module, they will not delete the project.