So you want to remove the glass with lettering for a plain piece of frosted glass?
If the letters can be removed, you can buy a spay on frosted glass product. I would apply the frosting to the back of the glass. If you can not get the letters off, any hardware store can cut a piece of 1/8" glass to your size. Then frost the back and install. I used the frosting spray on a bathroom cabinet that I put in a powder room so as to hide all the stuff in side. You can make it as opaque as you want it by applying additional coats. http://www.walmart.com/ip/Rust-Oleum...Spray/17011140
Another way to achieve frosted glass is to sandblast one side. I cut a piece of 1/4 glass I had to make a shelf for below the cabinet and sandblasted one side, it turned out very nice. I would have done the same for the cabinet but could not remove the glass..