If you have a 10-year China visa in your current or previous passport that has not expired yet and want to cancel that, you can only cancel it if you are applying for a new visa type. i.e.- Have a tourist visa and need a business visa. If you are cancelling it to apply for the same visa type, the consulate will not allow it, since you can still use the valid one to travel- you will need to bring the passport that contains the visa along with a valid Passport.