Am I sinful for withdrawing usurious interest from the bank to pay my father's house rent, knowing that I do not benefit from it and have advised him to leave it?

It is not permissible to accept agency for withdrawing usurious interest, because the owner of the interest is not allowed to benefit from it. Your action in doing so would be considered cooperation in sin, and Allah Almighty has said: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." It is obligatory to advise the father gently to abandon usurious dealings and to apologize for withdrawing the forbidden interest, while it is possible to withdraw the original deposit amount.