Magos is not perfect for that. If you seek to remove a whole group of polygons connected together, that may be ok. For example if you have a square surface for glow, you just shrink it to one vertex that is invisible, just like CMarket said. But if you want to remove a Grunt's helm... forget it. You will just shrink the horns so they make holes into the orc's head. Not to mention that in some models errors may occur like a stripe coming out from the shrunk vertex that is not supposed to appear.
Conclusion: Use Vertex Modofier to DELETE vertices, not shrink them together.