How to remove the grid from a zone in Omega
Could you elaborate on what it means not to be gridded inside a zone? If you just make a single region inside the zone that is as wide as the zone, then you could lay out content in the region however you want. Your CSS would just have the zone or region class as a prefix to anything else in that region.

Or, are you trying to get rid of the gutters? If so, you could make a custom grid of some number of columns with zero-width gutters. Then you have to add padding and margins yourself to your content. I have a site with an Omega grid-based layout with zero-width gutters, and do some non-grid-based layout inside certain regions.. For instance, I have pairs of images side by side inside the right sidebar. They are not aligned with the grid columns.