This is the method used to withdraw USDT in $Bittoken (BTT) Mining.

After you complete a P2P trade and sell your $BTT Tokens, if you want to withdraw your money to any exchange, this is how you can do it.
Register here:

When you register, you will receive 10,000 RP.
As I mentioned before — on the 16th of every month, they automatically convert users’ RP points into BTT Tokens. After that, you can sell the $BTT Tokens instantly through their P2P marketplace and withdraw your money.
However, I advise you to hold your BTT Tokens if you are interested, because their team is constantly working to improve the Bittoken ecosystem, and in the future the price may rise higher than it is now.