Why do I not have the option to vote to delete? I'm not fussed about deleting, I can vote to close it but, as I have 20k score, I thought I should have these extra options? https://superuser.com/help/privileges/trusted-user
You don't. Or more specifically the question has not met the criteria for you to try to put it out of its misery.
Voting to delete questions with a score of -3 or lower immediately after they are closed
The question needs one more downvote and to be closed.