I had a website at [site.example.com
I have deleted the website. It was on wordpress. Now I want to let Google know that the website is permanently deleted while also informing users that this site is no longer available. The users will obviously continue to come on different links. So I want them to be redirected to a page index.html in the root directory to inform them about unavailability of website.
How do I do that. So that search engines quickly understand and remove the site from results. While people coming from other non-organic links are also redirected properly to a page.