It all depends on the type of copyright that was put on the song you remixed. If the original song had specific copyright reasons prohibiting you from remaking it, you won't be able to upload it. However, if the song is in the public domain or has fair use rights, you may remake the content and upload it to your channel, to assume you actually did make some sort of change and not take the original song as yours. Different artists have different restrictions on different songs, so be sure to check out a copyright page of a specific artist if they have one!
Remember, when YouTube finds a copyright song on your video, it isn't a strike, it's only a warning. When you get the warning, you can always disable the audio or delete the video so a strike doesn't happen (you'll know if you got striked rather than warned).
Jordan Johnston wrote:
You can only play 30 seconds of a copyright song unless you have permission I believe.
Completely wrong. That's for education purposes authorized by the government (for the US, may vary in other countries).