No, there's no way to disable groov's grid.
The grid's there to enable groov's scaling functionality: the same view is clearly drawn regardless of whether you're using a browser window that's 480 pixels wide or 1920 pixels wide.
The grid itself is always 96 units across horizontally on a desktop view, and 32 units across on a mobile one. For a lot more detail on how we render it, there's a tutorial describing it up on my personal website here: Rendering groov with ClojureScript. Search for "Gadgets in groov are positioned on a grid" to find where it starts talking about the layout.
That's not our real implementation (we don't use ClojureScript in-house), but it's a good description of how the grid works internally.
With all that said: you might have decent luck with SVGs if you draw them with a grid in mind: make the major bits of them always multiples of 10 pixels across, for example. If you know ahead of time what window size you'll be displaying groov at (kiosks, for example), you can draw your graphics at that size in the first place.