Afforess
The White Wizard
Rams and Battering Rams and Siege Rams... Just the first one or two, or all three?
Rams definitely don't have much of a lifespan or use in AND (More so in C2C but even then not for long) so I wouldn't think it too bad of an idea to remove them.
I'd need to look to double check, but just Rams.
Another less extreme possibility is to just code some sort of "hack" in the AI to tell them to never build those units based on some XML value.