can you remove the side protection

Yes, easy and simple! Only need two hands and a tiny phillips head screwdriver ("Eyeglasses screwdriver", PH000, PH00, 1.0, 1.5) 1.) Open both arms of glasses 2.) On one arm, remove little phillips screw on inside of arm, and save for later (near your temple, the one securing the sideshield) 3.) Fold this arm in to body 4.) With one hand, grip arm where lettering is (with arm still folded in to body, so that sideshield can slide out) 5.) With other hand, grip sideshield 6.) Pull the arm and sideshield away from each other, while wiggling the sideshield until they seperate. (The first time will be harder, but keep pulling and wiggling and increasing pressure until they come apart) 7.) Repeat steps 2 - 6 on other arm 8.) Put screws back into seperated sideshields and store for later use

What are the dimensions? Will they fit someone with a big head?

They fit comfortably on my head and I have quite a large head myself, they also are rubberized inside which should cushion any discomfort.

Yes. These glasses have an anti-fog coating.

Ms z87+ what’s ms stand for? why it says ms instead of ansi?

Hello - Thank you for your inquiry. The "MS" stands for Magid Safety, the marking requirements of the ANSI Z87 standard require the manufacturers Identification.