When you die in the nether or the end, you get a clone. However, if you use the /kill command RIGHT AWAY after you die, the clone goes away. Just tested it, and it works.

Someone else told me about using /kill, but it never worked for me because I was using the command too long after I died.

No longer have to worry about having to wait several hours to use all the functions. Enjoy.

thanks antonyoo!

Just a clarification, you just need to die in any way, it doesn't have to be /kill. Also, I'm pretty sure you need to die in the world that you developed the clone.