I dont bother, rinse it out with fresh water and it's fine staying wet indefinitely.
If wet, keep wet. If dry, keep dry.
For longer term storage:
Dissolve 1/2 tablet Steramine in 2 Liter bottle of water. This can take a couple of hours.
Wash thoroughly with clean fresh water. A mild detergent or hand soap can be used but no harsh chemicals.
Inflate the wing with some fresh water. One pump of liquid antibacterial hand soap or baby shampoo. Slosh around and let drain from Over Pressure Valve and inflator hose.
Flush wing with fresh water at least twice.
Use the Steramine and let sit for an hour.
Drain the wing through the hose. Unscrew the hose and let dry. You can insert a length of cloth through the opening to where the water pools inside the wing to help wick the moisture out.
Clean the hose with a brush? Maybe when you are already servicing the inflator.
The K style inflators found in most wings should last forever just washing and lubricating periodically.
Some people use scotch guard on the nylon fabric or food grade spray silicon to keep it "fresh". It can help but sunlight will fade colors on any gear.
Old wives tales: coca cola as anti bacterial. White wine to kill viruses. Talcum powder for some reason.