They can’t. The debt owners get the property when they stop paying. Some legalities to actually foreclose but the debtors hood first position on thr property.
They may not want it.
There is more here than meets the eye. The loan matures in November 2023. So, the borrower is giving up the property for six months of mortgage payments. Unless there is a huge balloon payment they are giving up the building for very little money.
I suspect the real scenario is that a default and sale of the property will wipe out contracts that Park has with various unions and even with San Francisco. The loss on the building may be less than the projected losses from being forced to operate in a city that has turned itself into a sh*t hole.