To sell your USDT for Nigerian Naira, you can use a cryptocurrency exchange that supports USDT and Nigerian Naira trading pairs. Qxchange is one of the popular exchanges that support this pairing. First, you'll need to create an account on the exchange and complete the necessary identity verification steps. Once your account is verified, you can deposit your USDT into the exchange and place a sell order for Nigerian Naira. After your order is filled, you can withdraw the Nigerian Naira to your bank account. Be sure to check the exchange's fees and withdrawal limits before making any transactions.