It depends where you live but you have to open an account on an exchange and trade your Steem Dollars or Steem to Bitcoin and then sell your bitcoin in USD. Annoying process yes. Just google how to cash out money from steem it. Good luck @kingsibe
https://steemit.com/steemit/@lurker1/step-by-step-how-to-cash-out-your-steemit-earnings-to-usd