I believe the nanosuit can only be removed by machines since it is so skin tight.
In Warhead it was said that if you tried to remove it by other means it would literally rip the skin right off you! I hope Richard Morgan caught that because he said he never finished Warhead...

In one of the trailers you see that one guys, forgot the name if he did have one, face with the helmet of the suit transformed off.
I think its a safe bet tho, look at the suit, it looks literally like it would do that just from the looks.
But you do have another nanosuit in this game, could it be a difference.
If you remember the opening scene of Crysis 1 in the airplane, the old Nanosuits could also take the mask on and off, but the body is a whole different story.

Makes sense tho, its kinda like the armor in Halo, but LITERALLY skin tight.