What is the ruling on not paying usurious credit card debts due to accumulated interest, and settling for paying only the principal later, knowing that banks in Canada are usurious and repayment might mean assisting banks in usury?

You must repent, feel remorse, and seek forgiveness for engaging in usurious transactions, and return the principal capital to its owners without the interest. Do not delay or procrastinate in repayment, as you entered their country under a pledge of safety and concluded contracts with them regarding repayment.