You want to launder BTC into cash...so you want your BTC to be "scrubbed" clean of it's source and journey into becoming cash. The only way to do this would be to put the BTC into a cold wallet and then sell that cold wallet to someone for cash, where the negotiation and transaction occur in person (to prevent any online record of the discussion).

You could use a bitcoin mixer to scrub the source of the BTC before it hits that cold wallet, but that would only be needed to protect the buyer of your coins, not for you personally. Because once you sell that cold wallet your connect to it is gone.