How can one dispose of the forbidden interest from commercial banks, knowing that the questioner is currently in debt? Is it permissible to delay giving it out until the debt is paid off? What if he dies before fully disposing of the amount?

Usury is a grave matter. It is incumbent upon anyone who has engaged in it to repent to Allah by immediately desisting from it, regretting what has passed, and resolving never to return to it.

As for the ruling on usurious funds, if the dealings were due to ignorance of their prohibition, then it is not obligatory to dispose of them. Sincere repentance is sufficient, and one may benefit from them, based on the Almighty's saying: "So whoever receives an admonition from his Lord and desists, he shall have what has passed, and his affair is left to Allah." This includes a Muslim who was ignorant and excused for his ignorance if he repents. If he is poor, he may benefit from it in his capacity as a poor person.