The in-game menu tab HUD should list, rather at the top the option to display "Damage for Other Player", and two more similar options for BOs and yourself. From my experience, they effectively turn off the damage display. Be warned though, that some features from the HUD will stop working, notably the "Recently Damaged" setting (at least pre 1.2), as the internas seem to stop parsing damage altogether.
Comments
Where is that found?
-DisableDamage Whether to show/hide damage counters.
Tried it in Options/Advanced command line, but didn't work.