Verizon phones do not use Sim cards. They are only included with Blackberry devices such as the Bold for travelling overseas and accessing those carriers abroad. I actually do not even have my Sim card installed in my Bold. If you want to deactivate your Blackberry from Verizon, simply call customer service either from your device or from another phone.
It is my belief that anyone in the world may call you and you will receive their call while you are in the Verizon network. The SIM card allows your BB to receive calls when you are not in the Verizon network and there is GSM service available, either in the US or overseas. That is my 2 cents worth (and it is probably only worth 2 cents since I don't know that much about it, lol).