If you delete a site and then try to create a new site using the same URL you will probably get an error "The location you have chosen is not available". The learn more button will tell you "Your site name (and URL) can't conflict with an existing site name". This will happen even if you have permanently deleted the site because that function is currently broken. Google knows it is broken but so far they apparently have not been able to fix it.
Therefore I recommend that you remove all content from the site and rebuild it instead of deleting the site.