Eob, are you a micro distillery (i.e. legal)? Most home distillers are not going to have access to sugar/flavored vodka as a stock material, and will not know the term ngs (especially on a first post).
As for your question, the only way to separate is through distillation. Water the product down to 30% or less (it likely is already), then distill. If you run it through a pot still, take no cuts whatsoever, you should end up with the equivalent to the original ngs, pre-flavor, but at a lower abv. NOTE, depending upon what flavoring has been added, that may carry over on the distill. It may require additional distills (water down, rerun), or it may require distillation in a column still to pull out just the ethanol.
Also, you have to be concerned about scorching (and possible foaming) of the sugar based material.
Hillbilly Rebel: Unless you are one of the people on this site who are legalling distilling, keep a low profile, don't tell, don't sell.