Use a little bit of rubbing alcohol to dampen a soft cloth,then scrub the sticky area gently for a while and then wash it in the warm,running water.At last dry it with a soft cloth.Another way is using a hair dryer to heat the stickiness and then wipe it away.
You can put your sunglasses into warm water for a few minutes. And try to remove the stickiness with a piece of clean cloth. If you can't remove them in this way, you can put some soaps and rub them with a piece of clean cloth gently. And then rinse the soaps. If the lenses are made by plastic and the stickiness are hard too. You'd better take your sunglasses to an optical store. The optician can fix this for you. If he or she can't, you may need to buy a pair of new sunglasses.
This depends on which kind of stickiness you have on your lenses. If they are hard, you may remove your coating on the lenses as well. One of my friends just uses her nails to scratch the stickiness. She removes it by force. But the lenses are damaged. I don't know how to remove them in an easy way and without damaging the coating on the lenses. So you'd better take them to a nearby optical shop. If the optician can remove it for you, please let us know how to do it. Good luck!
Before you decide to remove the sickness on the sunglasses lenses, you need to know the material of the lenses whether it is plastic or glasses. Some cleaners work better on one surface, and some cleaners shouldn't be used on some materials. Try heating the sticker with a hair dryer and pulling it away before applying a cleaner. The heat may warm the adhesive enough to pull the sticker right off without any complications.