Am using binance app on my android
Follow what OmegaStarScream said, it is correct.
Make sure you send to bitcoin, the address start with 1, 3 or bc1. Any other ones are altcoins which are just sidechains.
Open your app -> from the bottom, select 'Wallet' -> Spot -> from 'Balance' select BTC -> Withdrawal, you will then get this dialog asking
Or better still, do this:
Open your app -> from the bottom, select 'Wallet' -> Spot -> withdraw -> select the coin and the image OmegaStarScream posted would be seen.
Check and recheck the address you are sending to, make sure it is correct.