This bug has now been fixed. Each choice was being assigned an ID of the text it was displaying, not the numerical ID of itself.
You should now be able to use the command REMOVE:1 to remove the choice you setup with CHOICE1:[text]:destination, and REMOVE:2 for CHOICE2, etc.
Please note that this id is not 1:1 with the visually displayed choice number if, for some reason, you create them out of order.