I'm a customer of betonline (tigergaming) and don't want to use coinbase, even through an intermediary wallet, because they can and will trace the account, so where can I sell my btc?
if youre country ready local exchanger is good you can sell in there
another you can sell youre bitcoin in bitfinex, bitstamp, kraken, localbitcoins, and much another exchanger
if you want still use coinbase service, you can mixer youre coin before deposit to coinbase
I think localbitcoins is ideal and global and will recommend that above the rest because it's a trusted escrow service where you can easily trade your fiats for bitcoins and vice versa.