How can a usurious loan that has been obtained be repaid? Is it permissible to use money from usurious deposits to repay this loan? Is zakat obligatory on what remains of this money in the savings account?

Borrowing with usury is Islamically forbidden. The borrower must repay the principal of the loan, not the interest, and must repent from usury. Investing in usurious banks is forbidden. The investor must withdraw their money and repent, and it is not permissible to remain in this investment to repay a usurious loan. Usurious interest must be disposed of by giving it to the poor or spending it on public welfare, and it is not permissible to benefit from it unless one is in need. Zakat is obligatory on the principal of the money in investment bank accounts if it reaches the nisab and a year has passed over it, even if it is difficult to withdraw, but zakat is not obligatory on forbidden usurious interest.