1999 Silverado Window Removal

[70TWO NOVA]

Hey guys,
Im going to be painting a 1999 Silverado extended cab and need to remove both side extended cab windows, but cant for the life of me figure out the proper way of getting them out. From what it looks like the entire window and its "casing" must be removed together as one, but it seems like it is siliconed to the side of the truck. Is that how the factory does it?
Either way, do I need to cut the silicone to romove the window and then re- glue it in when Im done? Any help or info about this is greatly appreciated. (pic below)
Thanks,
Brian