Removing an option when selecting another option.

[Bluefool]

Title kind of says it all, I'm trying to figure out how when an option is selected, you can remove another option.

Basically, the unit has a grenade launcher by default. If they take a laser, it replaces the grenade launcher. Creating both options, no problem, but I can't figure out how to get rid of the other one.

And, since I see it coming up, how can an option replace a unit? For instance, if a unit has an option of a suit that changes its unit type, how the heck do you do that?