Can unallowed passive losses from a rental property for prior years be taken in a year the property is no longer a rental?

Not when you do not have the passive income from what was the rental property at one time in the past.

The taxpayer must dispose of his entire interest in an activity in order to trigger the recognition of loss. If he disposes of less than his entire interest, then the issue of ultimate economic gain or loss on his investment in the activity remains unresolved.