If the parts don't void the CPO rules/qualification and the person taking over the lease (or dealer taking the car back) is/are interested in keeping them on the car that's possible too. I had the dealer cut me checks on previous cars for wheels BMW performance exhaust etc as they have been able to sell the car with the accessories installed . Other itmes such as suspension/springs/tunes/air intakes etc have to be taken in order to allow the dealer to CPO the car .
But in general taking them off is a good idea and just install the new parts (plus they're not used so no worries about wear and tear
)