The reset likely means that when they returned his taming on her dissapeared, unclear for now if he it can be dispelled anytime and he a done so before returing to their own world or it happened for the teleportation, there are esome stories where isekaied characters lose their powers after returning home, they didn't lose it, but maybe it was kicked back to lv.1.
But it goes against his feeling his other tamed beings, so I'm guessing he can dispel it? Probably taming is like slavery and that was why he was against it.