You cannot remove it. My brother plays one and I remember once after he spawned behind me, my camera sort of "clipped" under his mask and underneath, just standard human eyes were rendered so they didn't feel the need to add any custom work for the lack of eyes. As for their reasons they left it out, I am unsure. Perhaps they believed that the empty sockets would be too unsettling to a younger audience or might even warrant an M rating.
That would be my bet for the RL reason particularly give that while I don't know how accurate my friends and family were but I do know that when the race was explained to me, the in game reason was:
Me: "Ok. So, that's kinda cool but why do they wear that stuff over where their eyes would be all the time?"
they don't have eyes."
Me: "Yeah but, what difference does that make in such a diverse culture? I mean, who would care?"
Answer: "Well, it's not that they care
its just that it freaks the other races out so the Miraluka just took to covering up that part of their faces."