You can try LuLu Money to send funds from your US bank to Hong Kong and collect in cash. They have a stall in World Wide House. Just keep the receipts in case you have to declare it later on your taxes.
Here's the link:
https://www.lulumoney.com/dev/hongkong/remittances.php
Out of curiosity, what US bank do you use? There's a Bank of America and JP Morgan Chase in Central and I'm almost certain there's a Wells Fargo branch in Wanchai. Regardless, you still should be able to withdraw from the major banks' ATMs here as long as you have international withdrawals applied to your US bank account.
Hope that helps!