Leave the bag, fully emptied and all pockets opened, next to the largest trash can you can find. A note saying RUBBISH/垃圾 inside would also be nice.
This way it's not going to cause a security scare, and the airport's hassle of disposing it will be minimal. It's still basically littering though, and the right thing to do would be bring the bag to somewhere else where it can be properly disposed of.