I'm assuming that the one seller who didn't want the fake back gave you a refund and (smartly) didn't want to pay to have a fake returned. If you didn't get a refund, DO SO!!
As for what to do with the fakes, I certainly don't recommend putting money into have the "un-Coached."
Since they're essentially worth nothing as they stand, my recommendation would be to take a scissors and cut the full creed and the serial number. You can either leave a pocket with a hole or if it's a flap pocket, just cut out the whole pocket. If the bags have hardware that's stamped with "Coach" markings, that would be a problem since removing hardware would make the bag fairly useless. But if there's no Coach hardware, you could donate the generic bags that will no longer have any brand markings.
Remove and dispose of fake hangtags if the bags have them.