It took me buying a fixed sissy bar and luggage rack to realize how many times I didn't want to have it on my bike. National Cycle's Paladin's QuickSet(TM) Mounting Hardware makes their Backrest (with pad) and Luggage Rack removable. Even better, it is lockable with a discrete key-lock on the inside of the bracket. So not only do you not have to worry about the assembly disappearing, your passenger will feel more secure knowing it is locked into place.

National Cycle's website has detailed info and great fotos of the components. Since its not the cheapest add-on for your cruiser, shop around for the best price. However, the price is well worth the flexibility. You will be very glad you purchased a removable version very soon after installing it.