I push up the lifter (is that what's it's called?) and release the shells by depressing the catch that holds them in the magazine. It's easier, faster, and not to mention, safer, than cycling the rounds in and out of the chamber to unload it.
This x1000. Cycling a shotgun is the improper way to unload it. The shell latch/cartridge stop simply needs to be depressed at the mouth of the magazine tube to eject live rounds from the magazine. This is the same on Winchester, Remington, Mossbergs, Savages, and most, if not all other shotguns out there. When you rack the slide to load and then eject live shells, there's always the off chance that you will get a slam-fire or other malfunction that will cause the firearm to discharge accidentally. This is how one of my best friends was killed when we were in 8th grade. His buddy was showing him his new shotgun and was unloading it improperly by racking the slide repeatedly. His finger slipped onto the trigger during one of the cycles and wound up discharging it at near point-blank range into my friend's neck and head.
Here are detailed instructions on how to unload a shotgun (in this case, from Mossberg)
Or for those inclined to watch videos: