I think WordPress is blocking me on Google – and I don’t even use WordPress now, but the ‘discourage’ box remains?

The only thing the “discourage search engines from indexing” checkbox did was add a noindex tag to the header of your WordPress site. If you’re not using WordPress anymore that tag isn’t there anymore and it cannot have any effect. Any solution to the issue you’re experiencing now will not involve WordPress, so there’s not much more that can be said here.