It's available probably because Google simply don't care about the domain. Anyway, at any given time they might decide to go after it (because, you know, trademarks and what not).
Bottom line: You're asking for trouble. Delete the domain/ask for a refund. In the future, stay out of trademarks.
I would follow Adam Dicker's advice:
Change the whois contact information to fictional info.
Then have your registrar delete it from your acct.
Then, you will not show as the last registrant in domain history tools.