Put it back in the box and back outside the door where it was dropped off, and the next delivery guy to come by picks it up. My apartment building already gets multiple deliveries from Amazon each day, so partial-day rentals are theoretically possible without any more visits.
It'd be a logistics nightmare, but Amazon seems to be really good at solving those.
What if Amazon had a "Rent for 4 hours for $5" option on their site (right below the buy button).