Is it permissible for me to leave the usurious funds added to my bank account and instead give out their equivalent from my own money?

If the usurious gains (ribawi interest) are distinct and have not mixed with lawful money, then they must be disposed of specifically and not kept, because they are the very essence of what is unlawful (haram). However, if they have mixed with lawful money, then it suffices to extract an equivalent amount to dispose of them and absolve oneself.