What is the ideal solution for ceasing to deal with a usurious bank and repenting to Allah, knowing that the remaining installments cannot be paid and that selling the apartment may achieve a double profit?

You must repent from dealing with usury because it is one of the major sins and necessitates war from Allah and His Messenger. Part of perfecting repentance is to get rid of usurious interests. If it is possible to eliminate or reduce them, then you must hasten to pay off the installments, even if it means selling the house. However, if the usurious interests are binding and it is no longer possible to escape or reduce them, then there is no harm in benefiting from the house by living in it or renting it out.