You can send or get them to a local recycling facility. Visit the NYS Department of Environmental Conservation to see a list of such facilities.
Is there any security measure i must take regarding the plates disposal?
In fact, there are. You must make sure to separate your plates and put them in the recycle bin with some time between them, such as two weeks time.
Oh, right, quite obvious really. Is receiving these plates means that i'll get a new plate number?