What is it?
Allah forbade riba in the Qur'an. If you've earned interest from a bank account, ISA or any conventional investment, that money cannot be kept by you, but you should not throw it away either.
The agreed scholarly position is to give it to the poor or to general public benefit, without intending it as Sadaqah for yourself. You don't earn reward, but you fulfil your duty to dispose of the haram money cleanly.