What is the ruling on disposing of interest-based gains acquired from the bank over three years, while keeping the principal amount in the same bank after canceling the interest?

Usurious gains must be taken and spent on the welfare of Muslims, the poor, and the needy. It is not permissible to keep money in usurious banks except in cases of extreme necessity, such as the absence of Islamic banks. Otherwise, one must deal with Islamic banks, even if they are far away, because depositing money in usurious banks is considered cooperation in sin.