How can i remove my rusted and stripped deck screws from my deck boards?
You can do that, but some screws are very hard and you'll have a slow, noisy time of it. You'd want a high quality metal-cutting blade. Getting a gap between the decking and joists makes it much easier, too. 

If you aren't trying to salvage the decking, just pry the boards off the joists and then bend the screws that remain back and forth a few times. They'll snap off fairly easily, and you can pound any sharp stubs flat. You could make some circular saw cuts through the decking between joists to help you pry things loose.