If it is rooted, you could flash a new recovery ie TWRP, or Philz, which you can use to create backups, just be sure to tick all the boxes of what you want to backup. And if you're not happy with CM, you can restore the backup. I believe that you can flash the stock recovery through Odin, but I have never needed to, so I'm not 100% sure. If you have anymore questions don't be afraid to ask, I just might not know the answer :P.
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