To delete a website, first navigate to the corresponding page. Once you are on the relevant page, click on “Website actions” → “Website settings” → “Delete this website” (under “Website actions”). Please make absolutely sure that you are on the correct level, for example a subpage that you also want to delete. You can check this using the URL, for example. If you are on the top site level and then click on “Delete this site”, your entire SharePoint site will be deleted with all subpages and content!