If you use trusted mixing sites like Chipmixer, no one can trace you. You can't hide any transaction from blockchain but you can exchange them so that no one can trace you. For example, if you have BTC on an address and you send it to Chipmixer, you will receive another BTC in another address, so there's no link between your btc and the next one which you are going to use. So, you will be impossible to be traced.