Is it permissible to take a sum of money in exchange for relinquishing a prime commercial property, or to sublease it for an amount exceeding the original rent with the owner's consent?

It is permissible to relinquish the right of tenancy for a sum of money, or to rent the shop for a higher rent than what is due. This is known as "selling the key" or "khulu' compensation," as long as the tenancy period is still valid.