a choice, he pays rent for the floor space or you move it out of your
shop and put it on the side of street - he can pick it up any time ;-)

NO NO NO
If you put it on the side of the street and someone takes it, you are
responsible because you made it look like trash.
You can stick it out in your backyard or someplace like that as long as you
notify him. You have no obligation to safeguard it, you just have to use
slight care.