How can proseries preserve the depreciation schedule for future use, because currently in tax year 2019 depreciable property has not been rented

[IRonMaN]

Put in a retirement date in the asset worksheet but don't enter a dollar amount in the sales price box.

[Just-Lisa-Now-]

Why wasn't it rented?  Is it still a rental property?  Were they doing work to it that made them unable to rent it?  Just because they didnt have any rental income for a year doesnt mean you cant still deduct depreciation...youd need to provide some facts and circumstances to know for sure.