To replace sprite images and sounds in my game will easily change it to another RTS like Red Alert, but i'm nervous about the copyright now, I just want to produce my own game for fun so if I make RedAlert, will not upload to github again
You don't need to be nervous. Blizzard asking you to take down your copy of their assets is inevitable. No need to sweat it more than that, it's a fact of life.
You'll have to adapt the same strategy as they do, or any other engine remake: Host and share your engine, require the user to themselves supply the original game installation. That way your project is just a mod.
Another example of a great engine remake is "RttR" http://www.siedler25.org/ a remake of the Settlers II engine. They require a separate installation of the original game to play.
Which over the years and thanks to a massive effort of contributors have managed to create its own set of graphical and sound assets and is now a stand-alone game.
For Red Alert, there might not be much problems to do it since they made it a freeware[1] years ago and there are already plenty of projects around it.
Your code is still yours. The assets might not, but you can reproduce similar gameplay. Release it without the graphics and have people gather assets somewhere else (or find some free ones as suggested), as done with games like OpenTTD.
It is cool and impressive what you've achieved here, don't let that discourage you. Keep building these things.