This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
On the other hand, deleting a topic is generally not a good option. If the question has been answered, then the solution will also be deleted. And even if the question hasn't been answered, then a valid discussion could be lost.
It may be best to just follow up saying that the topic is no longer valid for you. This will lower the priority on getting an answer, but an answer may still happen -- which in turn, could help someone else in the future.