....remove it CAREFULLY!

Most non moving windows are installed with a sealent. Even if it's in a frame, the frame will have a sealent between the frame and the body to prevent leaks and whistling noises. You'll have to cut through the sealent...with a really thin blade knife.....or preferably a hot knife....and use a little gentle prying and proping up of the cut sections.

You can get a hot knife at a decent tool shop. It's like a knife...usually the blade is bent at a 45 degree angle about half way down and when you plug it in, it heats up.....and melts the seal.

Be careful though, it's easy to slip and cut yourself....and those windows are heavy.