How can I delete files off of a zip file on WinZip?

I am trying to open a zipped file on WinZip so I can delete these files that need to be deleted from the zipped file in order for my game to open. I am trying to download Real GTA 3. Everyone seems to be getting how to get it to work and I don't understand. I been watching videos on YouTube &' I don't understand what I'm supposed to do. I have an RAR file &' the zip file. What else do I need? Can somebody please help me with this process? I will really appreciate the help. Thanks.