Sure, it can be removed if the choke is a constriction (smaller) than the rest of the barrel. There are some muzzleloading smoothbores that have a chrome plating in the bore and of course, this will be removed if the choke is enlarged.
If the gun has a jug choke, where the bore gets larger than the main bore and then returns to the size of the bore at the muzzle, the short length of the original bore size at the muzzle can be removed and that would in effect, remove the choke. I don't know why anyone would do this though.