It was described to me as "awkward, but not wrong". So you can say it, but you'll be better keeping "non" before the verb it's attached to (even if there are other words in between).
Probably only if you qualify what you mean further: "Is est non Marcus, sed Hercules [est]"
No need to delete it, others may see it and get something useful out of it. :) It's the ablative form, so that might be where it came from.