What is the best, most secure and hard to trace way to transfer bitcoin to USD/EUR on a paypal account ?
The best and secured way to transfer your bitcoins into hardcash then local transaction is the only way.If you are doing this by any other way like banking or paypal your transaction will be recorded so it is possible to trace.
So contact a local bitcoin trader you can find them at localbitcoin site and contact them personally if you want to transfer your bitcoin for money.