some of the coolest dang looking soldiers are mounted! Thracian, Baktrian, etc. is it possible to remove the mount trait in their EDU (creating a new unit, not replacing)?

for example, now that my Baktrioi Agema is forever gone as a unit, i'd like Baktria to get a cool elite unit to replace them and what better than the stupidly heavily armored and awesome looking Late Kataphract? Perhaps as an elite archer spearmen unit, since there is not one of those. they already have the quiver on their knee.

is this possible? the model is already there, he's just sitting on a horse...