You obviously should not share your password with anyone. As others have said, typically you can not just choose any random payout method. The ones I have experienced, have been back to the credit card last used to deposit, or to a bank account in my name.
So the only way for a hacker to steal my money would be by logging on to my account and then play against another account and lose on purpose. In which case the winning account would of course be banned by the
poker site, and its owner reported to the police.
I think, you are chasing ghosts to be honest. There is probably a larger risk, that the poker site goes bust, than for someone to hack into your account. And as long as you dont keep your entire net worth on a single poker site, the risk is insignificant.