Is it permissible to rent out an apartment purchased with an interest-bearing loan to pay off the loan installments and be rid of the usurious interest?

It is not permissible to borrow from a bank with interest to purchase an apartment or anything else, because it is usury (riba). If someone did so out of ignorance, then "what has passed is for him," and he must repent to Allah. If he is able to extricate himself from the transaction by returning the principal to the bank and dropping the interest, then he should do so. If he is unable, then he should repay what was agreed upon and never return to such a transaction again, and the bank bears the burden of that sin. As for renting out the apartment, there is no harm in it, even if the installments are paid from the rent, for the apartment is now his property.